MUSEUM OF COMPARATIVE ZOOLOGY. 177 



Telepsavus (?)■ 



Plates III. and VIII. 



The most common mesotrochal larva at Newport is similar to one supposed 

 by Claparede and Metsclinikoff* to be the young of Telepsavus. The adult 

 Telepsavus has not been found in Narragansett Bay, and the alUed genus 

 Spiochcetopterus, to which Dr. E. B. WHson t doubtfully refers larvJB from the 

 Chesapeake Bay with many points of resemblance to those which are about to 

 be described, has also not yet been recorded from the locality where my studies 

 ■were made. 



A very common worm larva, which has the whole surface ciliated and an 

 apical compound flagellum, but in which no eciuatorial ring of cilia had formed, 

 is very commonly found at Newport in our dip-nets. These larva; (PI. VIII. 

 Figs. 12, 13, 14) resemble closely the young of amtopterus, but are larger, and 

 in°older stages more elongated. They resemble closely the young Telepsavus 

 figured by Claparede and Metschnikoff, and on that account are here referred 

 to this genns, although they have not been raised into any member of the 

 present "series. They might equally well, however, be connected with the 

 larviE which have been identified as belonging to the closely allied genus 

 Phyllocluetoptcrus. 



The young Telepsavus (PI. III. Figs. 6, 7) is quite large as compared with 

 other Annelid larvse, and can with the unaided eye be easily distinguished swim- 

 ming about in the water. The body is swollen into an almost globular shape, 

 and is divided into two regions by a mesial ring of cilia. In the youngest stages 

 of growth neither of these divisions is segmented. A fleshy triangular lobe, 

 rounded in front, is largely developed, and extends beyond the mouth on the 

 dorsal side of the head. The lower lip is bilobed. There are two cephalic 

 eye-spots in the youngest larva. The whole body is covered with cilia, and a 

 prominent median cilium is found on the prseoral lobe near its rim. The 

 mouth (m) has a triangular shape, opening below the lobe, and is surrounded 

 by fleshy lips. No tentacles or cephalic appendages are yet developed. 



The posterior portion of the body is short, tapering to the posterior pole of 

 the larva, which bears a segmented (?) tail (Fig. 7, a). The anus is dorsal in 

 larvse of this age. 



Almost the whole interior of both cephalic and caudal regions of the body 

 is taken vip by a large cavity (s) called a stomach, which occupies the greater 

 part of the anterior body region, and extends a short distance into the posterior 

 part. Its walls have a green color, while those of the body are brown and 

 pink. A diverticulum from the stomach extends forward in the ventral region 

 of the l^ody cavity below the oesophagus. The oesophagus in its course bends 

 twice upon itself, and opens into the stomach on the dorsal side. Its walls are 



* Zeit. "Wiss. Zool., XIX., 1869. 



t Observations on the Early Developmental Stages of some Polychaetous An- 

 nelides, Stud. f. Biol. Lab. Johns Hopkins Univ., Vol. II. No. 2. 



VOL. XI. — NO. 9. 12 



