270 ^Ir. W. S. Kent on a new Species (/Sagitta 



midway between these and the haroe hitcral falccs (tig. 2, b) ; 

 and it is in reference to the first-mentioned of these structural 

 peculiarities that the specific name of tn'cusj)idata has been 

 applied to it. 



This peculiar armature of the liead, just described, is the 

 more easily appreciated Avhen com})arcd with that of Sagitta 

 hqmnctata, represented in fig. 3, and sharply separates it from 

 that or any other recorded species. 



Fijr. 2. 



Fig. 3. 



Fig. 1. Sagitta tricuspidata, nat. size : a, alimentary track ; o, an ovary; 



sp, orifice of one of the spermatic cavities. 

 Fig. 2. TKad of the same, viewed from beneath, considerably enlarged : 



fi & h, the modified denticles ; c, the lateral falces. 

 Fig. 3. The same region, under like conditions, of Sagitta bipnnctata. 



(After Rusk.) 



In technical language, the characters of this new form may 

 be briefly drawn up as follows : — 



Sagitta ti'icusj^idata, sp. nov. 

 Body long, somewhat stout. Caudal region one-fifth of the 

 length of the entire body, exclusive of the head. Lateral fins 

 distinctly separate from one another ; the anterior pair smaller 

 than tlie posterior. Caudal fin moderately large. Falces bound- 

 ing the lateral margins of the head, eight in number on either 

 side, those occupying a median position being much the largest. 

 The anterior margin of the head bearing a slight prominence 

 on either side of the median line, and in which are inserted 

 three stylate setae, a similar solitary seta also occupying a 

 central position on each side between these and the lateral 

 falces. 



Entire lengtli of the body 36 millims. ; greatest breadth of 

 the same 5 millims. 



Habitat. The South Pacific. 



The integument of this .species, as preserved in spirit, was 

 smootli and very transparent, and appeared to be quite devoid 



