162 PROCEEDINGS OF THE ACADEMY OF [Jan., 



even coalesced. They also vary much in size, and the two series on a 

 radiole are seldom symmetrical. 



The collar is simple, cleft, but in contact and slightly inturned dorso- 

 medially. The dorsal half is low, of an even height, and has a shghtly 

 wavy margin. The ventral half rises very gradually to the apex of 

 the triangular lobes which nearly meet in the middle line l^ut diverge 

 distally. There are no lateral incisions. 



A pair of prominent tentacles are united with the middle of the inner 

 face of the undivided base of the palpi. They rise freeh' to a length 

 exceeding that base, and consist of a foliaceous proximal ^, and a nar- 

 row ligulate distal |. Besides these a pair of minute processes occur 

 side by side on the middle of the head disk, and probably represent the 

 true prostomial tentacles. 



The 174 to 184 somites, of which S are thoracic, form a slender, elon- 

 gated body, terete anteriorly, but very strongly arched above and with 

 a sole-like ridge formed by the ventral plates in the posterior part. 

 The lozenge-shaped anus is situated in a small pygidium. In the 

 thoracic region the segments are longer and distinct ; in the abdominal 

 they are very short and posteriorly much crowded. Here the body 

 walls are very thin and distended by the w^ell-filled intestine. The 

 ventral plates of the thoracic region are not elevated above the general 

 surface, but occupy the entire area between the tori. Thej^ are sepa- 

 rated from each other l)y deep transverse grooves, and the first from 

 the peristomial collar by a deep brown or black, apparently chitinous 

 line. The first is about 4 times as broad as long, the second 3 times, 

 and the others not over 1^ times. The first al^dominal plate is about f 

 as long as the last thoracic, the second is polygonal, and the others 

 become successively shorter to the caudal end and form a deeply 

 pigmented, narrow, sole-like ridge, divided from the anterior margin 

 of the third one to the anus by the faecal groove. The facal groove 

 divides the ventral plates continuously to the posterior margin of 

 somite X, around which and IX it passes obliquely to the right, and 

 then along the middle of the dorsum of the thoracic segments, on Avhich, 

 however, it is very faint. 



Dense tufts of setie occupy the dorsal portion of the setigerous tori 

 on II to VIII inclusive, and smaller tufts of very prominent setse pro- 

 ject from the ventral side of those of all abdominal somites. On 

 somite I are two setigerous lines shaped like the sides of a lyre, which 

 begin wdth a just perceptible curve slightly dorsad of the succeediiig 

 tuft of seta?, and diverge oljliquely forward in a nearly straight line to 

 the base of the collar, on which they extend as an intiu-ned loop of 



