12 Prof. M'lutosli's zVo/e5//-om M« 



ventral edge of the basal tissue of the branchise. On the 

 other hand, a considerable portion of each dorsal edge of 

 the base of the branchiae is bordered by a free and mobile 

 flap — the ventral ed^e adjoining the mouth. 



The body is of small size in the examples from Plymouth, 

 viz., about an inch in length and of the thickness of 

 stout thread, whereas in the Canadian forms it is be- 

 tween 2 and 3 inches long and as thick as a crow-quill. 

 De St. Joseph also found large examples at Rocher. It is 

 grooved dorsally in the anterior region, rounded posteriorly ; 

 whereas the ventral surface is more or less flattened, and 

 marked by the median groove from the anterior region 

 backward. Tiie tirst region has a variable number of seg- 

 ments, viz. five to eight (Langerhans, seven to nine). The 

 posterior region has from thirty to fifty. Toward the tail it is 

 flattened and tapered, and ends in the anus, which often presents 

 a lateral })rojection on each side. De St. Joseph describes 

 the body as brownish, with large spots of white. Tlie first 

 body-segment has two. oval eye-spots {Lan(jerhans\. Fauvel "^ 

 describes anal eyes, which are absent in the preserved 

 examples from Plymouth f. The first bristle-bundle consists 

 of simple bristles, with moderately tapered tips and distinct 

 lings. The others in this region have two groups — an upper 

 witii longer shafts, more tapered and slightly curved tips 

 with narrow wings, and a dense lower group of spatulate 

 forms with a process at the tip. The bristles of the middle 

 region form the usual bristle-pillar of rather short bristles 

 with striated shafts, comparatively broad striated wings, and 

 very finely tapered tips — two series, a longer and a shorter, 

 being conspicuous. The shaft has a distinct curvature at 

 the junction with the tip. The posterior bristles are fewer 

 in number, and have wings distinctly striated and very 

 attenuate tips. In glancing at small preserved specimens, 

 it is found that most have the posterior bristles directed 

 forward, and. in several the anterior have the same direction. 

 In the larger forms the anterior bristles are often directed 

 upward, outward, and slightly backward. The anterior 

 hooks, which occur on all the anterior segments except the 

 first, are circular with a sharp main fang, and above it a series 

 of minute teeth on the cro>vn (Langerhans shows about 

 twenty-four), and a moderately long base. Striae pass from 

 the neck to the base, after curving round the prow. These 



* Campag. Sc. p. 315. 



t Both are seen in small specimens kindly sent by Major Elwes from 

 Babbacombe. 



