BRANCHETHUS LATUM. 359 



teriorly it becomes strongly convex. There is a distinct median longitudinal 

 neural furrow, which becomes more sharply defined in the posterior region. 

 Neither of the types is complete posteriorly. One, having a total length of 

 47 mm., retains sixty-four somites. Its maximum width, exclusive of the para- 

 podia, is about 8 mm. The other specimen is 80 mm. long, has a maximum width 

 of 7.5 imn., and consists at present of nearly 126 somites. In both specimens 

 the first division of the body embraces twenty somites. 



The prostomium caudally is a little expanded. The main portion of the 

 prostomium is strongly subcorneal, distally truncate, the distal surface at present 

 showing a softer rounded eminence, which is probably contracted from a palpoid 

 article such as is present in Scaloplos, the types having been at some time, it 

 appears, partly dry. Relatively to the succeeding region the prostomium is 

 very small, appearing as a mere tubercle on the anterior face. No eyes are 

 present. 



The peristomium above is much longer than the second somite, with the 

 anterior margin nearly straight. The anterior margin on each side is a little 

 concave and curves obliquely caudad of ventrad, the peristomium then becom- 

 ing narrower and incomplete at the middle of the venter, on each side of the 

 venter ending in an acute angle, the two arms leaving a very obtuse reentrant 

 angle between them which is filled by the soft border of the proboscis. Above 

 on each side at the anterior border is a conspicuous nuchal groove or pit. 



The proboscis is very short, much broader than long, and is wholly free from 

 papillae, wrinkles, or other unevenness. 



The first metastomial somite, like the peristomium, narrows conspicu- 

 ously ventrad but less strongly so than the latter. In one specimen, at least, 

 it shows a slight median incision in the anterior border. The succeeding somites 

 are not narrower ventrally than dorsally. They increase in length to somite V 

 or VI, after which they remain of essentially uniform width to the end of the 

 anterior division of the body. At the widest part of the body the somites are 

 near five and a fourth times wider than long. The segments in the posterior region 

 of the anterior division and the anterior region of the posterior show a tendency, 

 particularly above, to be bent angularly a little forward at the middle, this being 

 more pronounced in one type than in the other. In the posterior division the 

 somites are much shorter, being only from one half to one third as long as those 

 of the anterior division. They are shortest in a region covering about twelve 

 somites beginning three or five somites behind the anterior end of the division. 

 In the median dorsal region of each somite, in the median groove, there is in 



