APPENDIX. 523 



THEMISTO CRASSICORNIS. 



Specific character. Superior antennre vei-y short, thick, biarticulate, fur- 

 nished along their under surface with numerous auditory cilia; inferior antennae 

 with a flagellum comiDosed of one short and one long joint. First two pairs 

 of pereiopoda having the carpi suhovate, smooth, and unarmed along the 

 inferior margin. 



Length, half an inch. 



Themisto crassicornis. Kroyer, Gronl. Amfip. p. 67, pi. iv. fig. 17. 

 Edwards, Hist, des Crust, t. iii. p. 85. Spence 

 Bate, Cat. Amph. B. M. p. 318, pi. i. fig. 12. 



The first two segments of the pereion are shorter than the 

 rest, which are subequal. The superior pair of antennae have the 

 peduncle short, the flagellum uniarticulate, curved downwards 

 at the extremity, and furnished along the inferior margin, for 

 about two-thirds of its length, with auditory cilia. The inferior 

 pair consist of a peduncle, of which two segments are visible, 

 and a long slender multiarticulated flagellum. The first pair 

 of gnathopoda are vei'y short, not having the carpus anteriorly 

 produced. The second pair of gnathopoda are not larger than 

 the first, but having the inferior angle of the carpus antei'iorly 

 produced. The first two pairs of pereiopoda resemble each 

 other ; the second pair is slightly the larger, having the 

 meros and carpus broadly distended, the latter fringed along 

 the inferior margin with a row of very fine short cilia, and a 

 few long equidistant solitary hairs ; propodos and dactylos 

 reduced in character to a biarticulate joint, that bends back to 

 form a prehensile organ with the carpus. The third pair of 

 pereiopoda are very long, quite as long again as the next suc- 

 ceeding pairs, having the propodos and carpus subequal in 

 length, and the former furnished on the anterior margin with 

 a comb-like row of fine teeth ; dactylos short and slender. 

 The two last pairs of pereiopoda are about half the length of 

 the third pair. The posterior pair of pleopoda is long and 

 simple. The telson is short and dorsally flat, having a central 

 process on the under surface that lies between the basal joints 

 of the posterior pair of pleopoda. Colour, orange. 



This species has been recently sent to us by Mr. Edward, 

 who has taken several of different ages off the coast of Banff. 



