THEMISTO LONGISPINOSA. 381 



STOMAPODA. MYSIDM. 



GENUS THEMISTO. H. GOODSIR. 



Generic character. " External antennae armed with a scale. 

 First, second, and fifth segments of the abdomen bearing fins like 

 the mysis. Third and fourth with the peduncles bi-articulate, 

 and each peduncle giving off two branches ; the external branch of 

 the fourth very long and slender, semi-articulated. 



Themisto lonc/ispinosa. H. Goodsir. 



Specific Character. " Superior antennal scale of the same length as the termi- 

 nal joint of its peduncle ; armed at its extremity with a thick tuft of hairs. In- 

 ferior antennal scale twice as long as its peduncle ; fringe not strong. Third 

 subabdominal fin with its internal branch minute. Internal branch of the fourth 

 with a few long hairs from the extremity only. External branch reaching from 

 the extremity of the caudal fins. Internal caudal fin truncated. 



"Long, three-quarters of an inch. Hab. Frith of Forth. 



" Description. The whole body of a dark yellowish or 

 greenish colour. Eyes large, reaching to the extremity of 

 the peduncle of the inferior antennae. The reticulated 

 portion black, and produced backwards inferiorly. Rostrum 

 very short but sharply pointed. First joint of the pedun- 

 cle of the inferior antennas very strong, the two following 

 slender ; the setaceous portion of the antennae arising from 



