[ 23 J 



II. On some Atlantic Crustacea from the ' Challenger ' Expedition. By Dr. R. v. 

 WiiiLEMOES-SuHM, Naturalist to the Expedition. Communicated by Prof. Wyvllle 

 Thomson, F.B.S. Sf L.S. 



(Plates VI-XIII.) 



Read May 7th, 1874. 



AMONG the great quantity of deep-sea Crustacea which have been brought up during 

 our cruise in the Atlantic, either by the dredge or the trawl, I hare selected the most 

 interesting ones for immediate description. Besides, readers will find in this paper the 

 description of both sexes of an interesting Nebalia from the shallow water of the 

 Bermudas, some remarks on the structure of Cystisoma, and a note on the develop- 

 ment of a Land-Crab from the Cape-Verds. Some of the deep-sea forms, the Wille- 

 moesice (Deidamice), Astacus, Zaleucus, and Gnathophausia, have been already figured in 

 ' Nature,' in the " Notes from the ' Challenger ' " published by Prof. Wyville Thomson ; 

 and a short description, taken from my first notes on the subject, has been added. In 

 this paper it is now intended to give a more detailed account of their structure and their 

 systematic position. The paper is divided into the following seven parts : — 

 I. On a blind deep-sea Tanaid. 



II. On Cystisoma Neptunus (Thaumops pellucida). 



III. On a Nebalia from the Bermudas. 



IV. On some genera of Schizopods with a free dorsal shield. 

 V. On the development of a Land-Crab. 



VI. On a blind deep-sea Astacus. 



VII. On Willemoesia (Grote), a deep-sea Decapod allied to Eryon. 

 I have only worked out such species as, from their structure and zoological affinities, 

 present a greater interest or belong to groups about which we had a satisfactory lite- 

 rature on board. Should, nevertheless, a want of literary information be remarked in 

 some point or other, the reader is asked kindly to remember that this paper was worked 

 out on board a ship cruising in the Atlantic. 



H.M.S. 'Challenger/ 

 Cape of Good Hope, November 1873. 



I. On a blind deep-sea Tanaid. (PL XII. figs. 1-9.) 



During our cruise in the Atlantic, members of the Anisopoda tribe were found twice. 

 Pirst, on the 2nd of May a real Tanais was got from a depth of 1700 fathoms off the 

 North- American coast ; I cannot determine whether this animal belongs to a known 

 species or not. Later, when cruising among the Azorean islands San Miguel and Santa 



