1/8 BULLETIN OF THE 



thicker thau those of the stomach. The intestine is short, slightly coiled, and 

 opens externally through a dorsal anus. The " ventral gland " (v g), indicated 

 by a depression in the external body wall on the ventral side of the anterior 

 body region, has not yet appeared. 



The above larva is easily distinguished from the young Phyllochcetoptenis 

 (Fig. 16) of about the same age, by the absence of dorsal median eye-spots near 

 the long cilium on the prseoral lobe of the head. 



In the next oldest larva (Fig. 5) of Tclepsavus, we find that a new pair of 

 lateral eye-spots has formed, and two slight projections, one on each side, at 

 the base of the head, now appear. These last-formed bodies are the begin- 

 nings of cephalic appendages, which later attain a great development. In other 

 particulars, the two larvse differ very slightly from each other. 



The next oldest larva (Figs. 8, 9) to that last described is one in which we 

 have few changes, except those which result from the growth of the cephalic 

 tentacles. Segmentation of the body has begun in the posterior hemisphere, 

 but it has not yet appeared in the anterior. The present larva is almost iden- 

 tical with one of those figured by Claparede and Metschnikoff.* 



A larva somewhat older (Figs. 10, 12) than that last mentioned shows more 

 striking resemblances to other Annelid larvae than any of those which have 

 been spoken of above. Anterior and posterior portions share about equally in 

 the elongation of the whole body. Very slight changes have taken place in the 

 head, although the prseoral lobe has elongated and become more prominent, 

 and the median cilium has fallen off. 



On the ventral side of the body, a deep infolding ("ventral gland," vg) 

 of the body wall has taken place, at a point about one third the distance from 

 the ciliated belt to the front edge of the lower lip. Eight simple lateral pro- 

 tuberances,. each bearing a small cluster of spines, are found in the interval 

 between the cephalic appendages and the ring of cilia. On the fourth of these 

 parapodia, counting from the anterior, there are spines (in s) which can be 

 homologized with the cluster of spines on the fifth segment of Polydora.'\ These 

 bodies occupy in Telepsavus nearly the same position as the crimson pigment 

 spots (m s) near the " fourth segment" in Prionospio. The portion of the body 

 behind the equatorial ciliated circle has become segmented. The segmentation 

 constrictions are clearly defined, especially on the ventral side of the body. 

 Two pairs of lateral branchiae (b) appear on the segment just behind the ring 

 of cilia, and a single pair on the following.^ These appendages are richly 

 ciliated over their whole surface. The cesophagus (ce) extends through the 

 anterior part of the body cavity from the mouth to the seventh segment of the 



* Op. cit. 



t In Polydora, according to A. Agassiz, these spines are found on the fifth seg- 

 ment, which is really tlie fourth body segment if we regard the head as a single 

 somite. The clusters of red pigment in Prionospio are also found on the fourth 

 body segment. 



} In Dr. Wilson's larva " two pairs of branchiae " appear " on each of the two 

 segments behind the thickened ciliated ring." 



