312 Dr. J. Murie on the Skin &c. of the Rhytina. 



It results that the skin of Rhytina conforms in the main 

 to that of the Manatee (many sections of the latter having 

 been examined by myself), yet with a sufficient distinctness 

 of its own. As Brandt seems to infer from its corneous den- 

 sity, it is a kind of compromise between ordinary dermal 

 texture and horn material. 



Another important addition to previous memoirs, as given 

 by Dr. A. Brandt, is the fresh description, and, for the first 

 time, illustrations of the parasite which infested the skin of the 

 Rhytina. After treating of Steller's and J. F. Brandt's notices, 

 without agreeing with the latter in the adoption of the genus 

 SirenocyamuSj Dr. A. Brandt regards this parasitic crustacean 

 as most nearly allied to the Cyamus ovalis of Roussel de Vau- 

 z^me*. He further describes the characters &c. of the two 

 sexes [vide figs. 5, 6, 7, PL XIX., after his designs). 



According to our author, the differential diagnosis between 

 Cyamus ovalis and Cyamus Rhytince is as follows : — " C. 

 Rhytince distinguitur a G. ovali^ cui valde affinis, primo articulo 

 corporis antice minus emarginato ; manu pedis primi paris 

 latiori ; dente anteriori secundi paris longiori, digitiformi ; ap- 

 pendicibus branchialibus laminis cornels nigro-fuscis incras- 

 satis munitis." 



Bemarks concerning Dr. Liitken'st genus Flaty cyamus^ the 

 young stages of Cyamus^ and derivations of these and kindred 

 forms conclude his section on the parasite. 



Before summing up, some statements of Herr Pekarsky and 

 others are given relating to the experiences of the old northern 

 hunters. In their expeditions the flesh of the Rhytina was 

 freely eaten, the fat regarded as equal to butter, and also used 

 for lamps ; and out of the skin capital boots were manufactured. 



Dr. Alex. Brandt concludes by three jJi'opositions : — 



1. Contrary to the common wide-spread acceptation, the 

 Rhytina^ originally similar to the rest of the Sirenia and 

 Cetacea, possessed a smooth superficial layer of skin. 



2. The ridges and furrows of the Rhytina-skin are mainly 

 due to the ravages of the Cyamus ovalis, Rouss. 



3. In its histological structure, the skin of Rhytina does 

 not essentially differ from that of Cetacea and Sirenia ; it is 

 constructed, like the head-plate, of elongate filamentary cuti- 

 cular papillge, which, by Steller naming them canals, gave 

 rise to misconception. 



From the first two of these deductions I would venture to 

 dissent. In all the Cetaceans which have come under my 



* Ann. d. Sci. Nat. 2^ ser. torn. i. 1834, p. 259, pi. 8 ; and Spence Bate, 

 Cat. Amphipod Crust. B. M., Lond. 1862, p. 367, pi. 58. 

 t Conspectus Cyamidarum borealium. 



