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"A new species of stygobitic isopod from Cerro Colorado Cave, Municipality of Apazapan, near Xalapa, Veracruz, is described. The new species is placed in Mexistenasellus due to the lack of eyes and pigmentation, a head distinct from pereonite 1, and 2 well developed pleonites. Other characters, such as the number of setae in the dactyli of the pereiopods, show slight variations from the original description of the genus. The new species can be distinguished from the previously known 7 species in the genus by the shape of the head, the proportions of the pleotelson and length of uropods. Color in life is pink as is characteristic of the species of Mexistenasellus. A key to the species of Mexistenasellus is provided."

Mexistenasellus floridensis sp. n. is described from Hole in Wall Cave, Jackson County, Florida. The discovery of this unique isopod nearly doubles the range of the Family Stenasellidae in North America, which was previously known from Oaxaca, Mexico to southern Texas, USA. This is the first stenasellid reported swimming in the water column of a cave, a curious finding for an isopod that belongs to a group that is generally more adapted to inhabiting interstitial spaces. Mexistenasellus floridensis occurs syntopically with the subterranean asellid Caecidotea putea. Both species have been observed swimming in the water column, although neither has apparent anatomical adaptations for swimming as compared to the natatory pereopods of Remasellus parvus, an asellid that occurs in caves in Alachua, Madison and Wakulla counties, Florida.

Mexistenasellus floridensis sp. n. is described from Hole in Wall Cave, Jackson County, Florida. The discovery of this unique isopod nearly doubles the range of the Family Stenasellidae in North America, which was previously known from Oaxaca, Mexico to southern Texas, USA. This is the first stenasellid reported swimming in the water column of a cave, a curious finding for an isopod that belongs to a group that is generally more adapted to inhabiting interstitial spaces. Mexistenasellus floridensis occurs syntopically with the subterranean asellid Caecidotea putea. Both species have been observed swimming in the water column, although neither has apparent anatomical adaptations for swimming as compared to the natatory pereopods of Remasellus parvus, an asellid that occurs in caves in Alachua, Madison and Wakulla counties, Florida.

Troglobitic isopods of the family Asellidae, comprising about 42 species (Fleming, 1973), are widespread in the eastern United States, mostly in non-glaciated areas, but extending into some glaciated parts of Illinois and Indiana. To the west, troglobitic asellids range to central Kansas, Oklahoma and Texas. West of this area, if we exclude the 4 Mexican species of Mexistenasellus (Cole and Minckley, 1972; Magniez, 1972; Argano, 1973) which belong to a separate family, Stenasellidae (Henry and Magniez, 1968, 1970), only 2 troglobitic asellids are known from North America: Asellus californicus Miller (1933) from northern California and Conasellus pasquinii Argano (1972) from Veracruz state, Mexico. The 3 new species of western troglobitic asellids described herein extend the records of blind asellids in North America south to Chiapas state, Mexico, and north to central Alberta, Canada (ca. 53''N), and add a second species from California. The new species from Chiapas is very similar to Conasellus pasquinii Argano (1972); the new asellids from Alberta and California show no close affinities with known species. The generic status of North American species of Asellus is still unsettled. Henry and Magniez (1970) divided tlie species between Conasellus Stammer (1932) and ,Pseudobaicalasellus Henry and Magniez (1968) except A. tomalensis Harford and ... A. californicus Miller, which they believed to be closely related to far-eastern forms belonging to Aseltus (Asellus) and Nipponasellus Matsumoto (1962). I have indi" cated that this is unlikely for A. tomalensis (see Bowman, 1974); the case oi A. californicus will be discussed later in this paper. ' '""'*