OF THE CRUSTACEAIf GENUS BATHTISTELLA. 34S 



Thomson*, the characters of which I have lately discussed t at 

 some length, calling attention to its affinity with the Palaeozoic 

 GamjpsonychidcB and their allies. 



Anaspides (PL 20. fig. 2) agrees with Bathynella in having no 

 carapace, in possessing natatory exopods and plate-like epipods 

 on the thoracic limbs, and in the fact that the maxillipeds are not 

 greatly different from the succeeding ajDpendages. Like Bathy- 

 nella, Anaspides 'wa,'s, originally described as having eight free seg- 

 ments in the thorax ; but I have pointed out that the so-called 

 first thoracic somite is marked off from the cephalic region not 

 by an articulation but by a groove on the integument, aud that 

 this groove probably represents -the line of junctijn of the man- 

 dibular somite with that of the first maxillge. Anaspides there- 

 fore differs from Bathynella and agrees with the Arthrostraca, 

 in possessing only seven free somites in the thoracic region. In 

 many other characters Anaspides shows important differences 

 from Bathynella : the antennules are biramous, there are two 

 epipodial lamellae on each of the thoracic legs (PI. 20. fig. 4) 

 (except the last pair), the second or basal joint of the thoracic 

 legs is unusually small, while it is large in Bathynella, the 

 abdomen carries a complete series of appendages, the telson 

 is simple and undivided. 



Assuming, however, as I think we may fairly do, that such cha- 

 racters as the small size of Bathynella, the absence of eyes, the 

 simple form of all the appendages and the reduced number of 

 joints in most of them, are due to degeneration correlated with 

 its subterranean habitat, there would seem to be adequate 

 grounds for suggesting that Bathynella is at all events less 

 distantly related to Anaspides than to any other existing 

 Crustacean. 



Many of the characters in which Anaspides agrees with the 

 Palaeozoic Gampsonychidce are also shared by Bathynella ; and in 

 some points, such as the presence of a free first thoracic somite 

 and of only a single series of epipods, the latter may even 

 approach some of the fossil forms more closely than does 

 Anaspides. 



* Trans. Linn. Soc. (2), Zool. vi. (3). 



t Trans. Roy. Soc. Edin. xsxviii. pt. ir. no. 23. 



