PELOGOSPH^RA, A LARVAL GEPHYREAN. 283 



pallasii. And furthermore the proboscis or everted portion 

 would, owing to its dorsal position, form a protuberance on the 

 dorsal side of the mouth which would be situated, as in Echiurus, 

 at its base. Perhaps to facilitate the eversion of this part of the 

 digestive tract another outpouching (p) occurs on the ventral 

 side of the gut, but its cells though columnar lack the ciliated 

 coat, and it is without special retractor muscles. 



This reference to Echiurus does not necessarily prejudice one 

 in favor of the belief that the larvae in question belong to this 

 or allied genera. Setae are totally lacking, there are no signs of 

 segmentation, and so far as may be seen there are no cilia on the 

 external surface of the body as in other gephyrean larvae. For 

 the present, at least, the question of systematic relationships 

 cannot therefore be definitely determined. 



Ventral to the gut in this same region are two spheroidal 

 glands (g) in close contact with each other. In life they bear a 

 fairly close resemblance to ova, which doubtless led Mingazzini 

 to describe these organs as the gonad. Each is composed of a 

 mass of pyriform cells, densely packed with a finely granular 

 vsecretion from which ductules extend toward the inner face of 

 each gland. A small duct, opening into the pharynx or oesopha- 

 gus, extends anteriorly a short distance, and then bending ven- 

 trally it passes between the two glands whose ductules unite 

 with it. 



Beyond this point the digestive tract pursues an irregular 

 course, and bending on itself passes dorsally to the anal opening. 

 Three distinct divisions are clearly defined, the oesophagus, 

 stomach-intestine and rectum. The first of these is of irregular 

 outline, of relatively large caliber and its walls throughout are 

 composed of columnar cells bearing a coat of delicate cilia. In 

 the region of the stomach-intestine it narrows considerably and 

 its walls become longitudinally folded. The stomach-intestine 

 (5) is at first a comparatively large sac with highly glandular 

 walls, each gland cell pyriform with the swollen distal end dis- 

 tended by some lightly staining, vacuolated secretion. Diatoms 

 occur in this section of the tract together with small quantities 

 of some other material, all of it enveloped in a stringy looking 

 coagulum. Although the gut is narrowed for a considerable dis- 



