80 Prof. M'lntosh's Is'otes from the 



occur on the thorax and part of the abdomen, this view is 

 not without doubt. 



So far as can be observed in the photographs given by 

 Sir William Turner*, and from other figures, no uniformity 

 exists in the occurrence of the fissures in the ridges, which 

 in this species are narrow and fine in front in comparison 

 with those in the common rorqual, and still more in contrast 

 with the massive ridges in Mecjaptera. Yet in the common 

 rorqual the junction of two of the jugal ridges occurs several 

 times on each side, and in their course backward several of 

 the Large ridges are split into two. 



2. On some of the Species q/" Prionospio, Malmgren. 



A Canadian Prionospio, dredged by Dr. Whiteaves in the 

 Gulf of St. Lawrence, Canada, presents certain differences 

 from that described by Malmgren, while ap[)roaching that of 

 Sars. No complete example is in the collection and no 

 satisfactory fragment of the posterior end, all presenting 

 signs of mutilation and regeneration. The proboscis was 

 extruded in every case, so that the snout was more or less 

 distorted, the protruded organ forming a button-like process 

 on the end of a short cone. The snout (PI. \1. fig. 1) had 

 the ordinary truncate anterior border without a trace of eyes, 

 but on the dorsum a cephalic ridge extended along the 

 median line and terminated posteriorly in a pointed process 

 like an adnate tentacle aijout the line of the third feet. The 

 body presented the normal outline, raid when complete 

 ])rol)ably had about one hundred segments, the number 

 given by jMalmgren for the northern species. 



In the anterior third of the body a transverse section 

 presents well-developed cuticle and hypoderm, the latter 

 especially being thick in the lateral processes and on the 

 ventral surface external to and at the sides of the nerve- 

 cords. The dorsal longitudinal muscles are of average size, 

 and the inner ends are slightly tapered as they a|)proaeh the 

 middle line above the dorsal blood-vessel. The ventral 

 l(;ngitudinal muscles, which occupy a limited elliptical area, 

 are also of average bulk, and in section show vertically 

 curved fasciculi externally and nearly horizontal fasciculi 

 internally. In this region a powerful series of fibres passes 

 from the doisum about the middle of the longitudinal 

 muscle, which is pieiccd, to the mid-ventral surface, probal)ly 



• ()l>. ill. J)]'. CO \- (>1. 



