CHAETOGNATHS OF MISAKI HAEBOK. 



17 



8. Sagitta regidaris, nov. sp. 

 (Fig. 8.) 



A small-sized species. Larger specimens 7mm. long and 0,5mm. 

 broad. The caudal segment is nearly 7s of the whole length of the 

 body. The epidermis is thick throughout the entire body, but especially 

 so in the anterior part of the trunk, so that the head is not constricted 

 from the body as in other species. The muscular layer is very thick. 

 The two pairs of lateral fins are separated, and each fin has the shape of 

 a semi-ellipse. The first fin is short, being nearly half as long as the 

 second fin which lies mainly on the caudal segment. Seizing- hooks 7 ; 

 anterior teeth '2-4, posterior teeth 5-7. 



The intestine has two diverticula at its beginning. The mature 



ovaries may extend nearly to the anterior 

 end of the first lateral fin. The corona 

 ditata is long and elliptic, and is on the 

 trunk segment. The. tactile prominences 

 are well developed and regularly arranged. 



As Grassi says, there are in all chae- 

 tognaths two kinds of tactile prominences : 

 one kind is larger, and the hairs, which are 

 longer than those on the other kind, 

 are arranged in transverse planes, while 

 the second kind is smaller and has shorter 

 hairs arranged in longitudinal planes. 

 These two^prominences are arranged in 

 this species regularly in alternate trans- 

 verse rows except in the dorsal and ven- 

 tral median lines of the body, where the 

 small prominences of the second kind lie 

 n a longitudinal row at irregular intervals. 

 In the above wood-cut where A shows 

 the dorsal and B the ventral surface, 



B 



Wood-cut 1. 

 e=eye, c = corona ciliata, 

 ag= abdominal ganglion. 



