THE Cir^TOGNATHA. 



71 



size, which makes the separation of young specimens from young of serratodentata and 

 similar forms extremely difficult. The table at least yields positive information of its 

 occurrence as high as 100 fathoms or less, between 150 and 50, and between 200 and 

 100 fathoms. Below the latter zone it failed in the closing-net, and probably does not 

 exist. But it may have reached a higher level than 100, for in three hauls in the open 

 nets at 75 and 50 fathoms I took young specimens which I cannot satisfactorily identify. 



The foregoing species were for the most part abundant and well-characterized. 

 But there remain a few specimens to which I dare not give a definite name, for want of 

 sufficient material. As they may help to extend the observations of some future worker, 

 I append a few notes on them. 



Sagitta sp. indet. ? juv. 



In open nets lowered to depths between 50 and 250 fathoms, and in one closing-net 

 (200-100), there occurred a number of small and immature specimens of a very slender 

 type, which I dare not assign to any species. Their figures, when summarized, are as 

 follows : — 



They occurred in the following hauls 



They resembled young so-ralodenlata, hut showed neither the characteristic hooks nor 

 serrations of the jaws. They bore a still stronger resemblance to drripiens, but the 

 posterior teeth seemed hardly numerous enough for that species. They might be young 

 decipiens, or zetesios, or possibly a separate species, but they are almost certainly not 

 youug fiircaia or macrocephala. 



Sagitta Pplanctonis, Steinhaus. (PI. 6. figs. ;?6-40.) 



Under this head I rank three well-pi'eserved sj)ecimens of doubtful relation. The\ 

 bear a close general resemblance to zetesios, but diff'er in that the anterior and 

 posterior fins are nearer together, the anterior fins reach further forward (in one to the 

 end, in two to the middle of the ventral ganglion), the widest part of the posterior fin is 



SECOND SERIES. — ZOOLOGY, VOL. X. 12 



