TRANSACTIONS OF SECTION D. — DEPT. ZOOLOGY AND BOTANY". 561 



MONDAY, AUGUST 19, 1878. 



The following Papers were read : — 



1. Report on the Present State of our Knoivledge of the Crustacea. 

 Part IV. On Development. See Reports, p. 193. 



2. On the "Willemoesia Group of Crustacea. By C. Spence Bate, F.B.S. 



Among the many ohjects of interest taken from the depths of the ocean during the 

 cruise of the Challenger, there were few that attracted more attention than the so- 

 called blind Crustacea. 



These were described by Mr. Willemoes-Suhm rather fully both in ' Nature ' 

 and in the 'Transactions of the Linnean Society,' — in the pages of the former under 

 the name of Deidamia ; but in the latter Mr. Grote, having discovered that this 

 name had been in use for a genus of Sphingidse, changed it to Willemoesia, in com- 

 pliment to the unfortunate marine zoologist of the expedition. 



Soon after it had been published it was recognized by those who had given at- 

 tention to the subject to resemble a small crustacean that Dr. Heller had described 

 among the " Crustaceen des siidlichen Europa," from a single male specimen in the 

 collection of the museum at Vienna, to which he gave the name of Polycheles 

 typhlops, belonging to the same group. I believe that I am correct in stating that 

 Mr. Wood-Mason was the first, in the ' Journal of the Asiatic Society ' for 1875, to 

 point out the resemblance between the Polycheles of Heller and Willemoesia of the 

 Challenger expedition. 



Each of these zoologists has described the animal as being blind ; and it is sup- 

 posed that on this character Heller founded the specific name of his species, the eyes 

 of which, he says, 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 Astacidae 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 ' Scyllaridae,' from which it differs essentially by the structure of 

 the antennae, the form of the chelae, and the narrow sternum. With the Astacidae 

 it has in common the possession of the leaf-like appendage at the base of the second 

 antennae and the chelate character of the pereiopoda ; in all other respects it differs 

 from Astacus. 



AVillemoes-Suhm says : " Among the living Decapoda Macrura there is hardly 

 a group with which Willemoesia could be said to be very closely allied. Nearest 

 to it are undoubtedly the " Scyllarinae ; "' but these, like all the genera of the 1'amily 

 Palinuridre, differ from it in the absence of the lamellar appendage of the second 

 antennae, 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 re- 

 ferred to the Astacidae, with which it has in common the presence of the antennal 

 scale." 



"The genus," says Heller, corresponds greatly with the fossil crustacean de- 

 scribed by Deshayes from the slate-quarries of Solenhofen {Eryon Cuvieri), since 

 1878. o 



