REPORT ON THE CRUSTACEA MACRURA. 11:; 



two forms. In W. [Polycheles] crucifera, as well as in Eryon the carapace has nearly 

 half the length of the whole body and in both forms its lateral borders are wing-like 

 expansions which are divided by two deep incisions into three portions. The anterior 

 border of the carapace is nearly straight in both forms." 



"Eryon was probably not blind; for the eye-stalks have been found in Severn 1 

 specimens. Its antennae seem to be somewhat more reduced than in Willemcesia; but the 

 second pair of them has, according to Desmarest, 'une ecaille assez large, ovoide et forte- 

 ment echancree.' This is the chief difference between Eryon and the Palinuridse, and 

 the same in which Willemcesia also differs from that group." 



"Milne-Edwards says nothing on the parts of the mouth; but according to Quen- 

 stedt they had a very large mandibula, one of the teeth of which was pre-eminently 

 strong. This is very much like what we find in Willemcesia ; but in the fossil genus 

 palpi were present at the base of the first and second gnathopods, which are wanting in 

 the living genus. The first pair of pereiopoda is in both forms longer than the following 

 ones, and terminated by a parr of long and slender chelse. In Eryon three pairs of 

 pereiopoda, in W. leptodactyla five, and in W. crucifera four are terminated by chelae. 

 The form of the last pereiopod in E. arctiformis is exactly the same as in W. crucifera ; 

 and the abdomen [pleon] of these two forms is, as the above-mentioned figures show, so 

 very much alike in the two forms, that, if the last pair of pereiopoda and the pleon of 

 Eryon were presented to me without my knowing to what they belonged, I should 

 undoubtedly declare them to be parts of the genus Willemcesia. There are the same line 

 of spines at the top of the rings, the same wing-like expansions on both sides, and that 

 characteristic ' nageoire caudale, dont la lame mediane est pointue et les quatres 

 lames laterales moins longues que la mediane et hastiformes.' Also the fine fringe 

 of hairs which distinguishes the caudal fin of Willemcesia is to be seen in the fossil 

 crustacean." 



"Eryon differs from the living genus chiefly by the presence of eye-stalks and of 

 palpi at the base of the gnathopoda. According to Quenstedt the latter were observed 

 only with some difficulty ; and their presence seems not to be beyond all doubt. I shall 

 only on my return be able to look myself over the original specimens and papers, and 

 then, I hope, be able to give a more detailed account on the relations of Willemcesia to 

 Eryon." 



But that anticipation, unhappily, was never fulfilled. Dr. v. Willemoes-Suhm, the 

 talented naturalist of the Challenger, died on his way home ; hence I thought it my 

 duty to quote his remarks in full. 



The fossil genus Eryon, from the bthographic limestone quarries of Bavaria, and 

 from the Lias of England, has long been known to geologists. According to Desmarest 

 it was first figured by Knorr and Walch iu 1775, and named Locusta marina by Bajer 

 in 1757. Schlotheim described it in 1820 under the name of Cancer macrourites arcti- 



(ZOOL. CHALL. EXP. — PART LII. — 1886.) Fff 1" 



