274 Mr. C. Spence Bate 07i the 



Each of these zoologists has described the animal as being 

 blind ; and it is supposed that on this character Heller founded 

 the specific name of his species, the eyes of which, he sajs, 

 are rudimentary ; and Willemoes-Suhm says that " the eyes 

 are entirely wanting ^ nor is there any place left open where 

 you might expect to find them." 



Both these observant naturalists have passed over the 

 peculiar character of the organ of vision that belongs to this 

 group of animals. Heller has classified it with the family 

 Astacidte in a division by itself; and they have both asserted 

 that it closely corresponds with the fossil genus Eryon. 



Dr. Camil Heller, moreover, says that it bears a strong 

 resemblance in the form of the body to the Scyllaridte, from 

 which it differs essentially by the structure of the antennas, 

 the form of the chelse, and the narrow sternum. With the 

 Astacidge it has in common the possession of the leaf-like 

 appendage at the base of the second antennse and the chelate 

 character of the pereiopoda ; in all other respects it differs 

 from Astacus. 



Willemoes-Suhra says, " Among the living Decapoda 

 Macrura tliere is hardly a group with which Willemoesia 

 could be said to be very closely allied. Nearest to it are un- 

 doubtedly the Scyllaringe ; but these, like all the genera of 

 the family Palinurid^e, differ from it in the absence of the 

 lamellar appendage of the second antennse, and in the presence 

 of palpi at the base of the gnathopoda, which, as we have seen, 

 are wanting in this new genus. Nor can it, for this latter 

 reason, be referred to the Astacidae, with which it has in com- 

 mon the presence of the antennal scale." 



" The genus," says Heller, " corresponds greatly with the 

 fossil crustacean described by Deshayes from the slate-quar- 

 ries of Solenhofen [Eryon Cuvieri)^ since also in this are 

 found a flattened carapace and similarly formed antennae and 

 pereiopoda. The hinder part of the body is much narrower 

 than the anterior ; and the leaf-like appendage of the second 

 pair of antenna is much enlarged. It forms a link between 

 the ^Scyllaridfe on the one hand, and the Astacidse on the 

 other." 



" It is very astonishing, indeed," says Willemoes-Suhm, 

 " that, among all the crustaceans known to us, Willemoesia 

 approaches most closely the fossil Eryontidse. If we com- 

 pare, for example, our figure of W. crucifera with the figure of 

 Eryon arctiformisj and the description of the ' Tribu des 

 Eryons ' given by Milne-Edwards (and probably taken espe- 

 cially from Desraarest's '■ Crustac^s Fossiles'), we find most 

 striking resemblances between the two forms. In W. crucifera 



