1883.] NATURAL SCIENCES OP PHILADELPHIA. 209 



tion I did not comprehend until 1 found an explanation in the 

 following paragraph in Claparede's Recherches sur la structure 

 desAnnelides Sedentaires, Geneva, 1873, page 76 : " M. de Quatre- 

 fages has discovered that in certain Serpuliens," to which family 

 Fahricia and Manayunkia belong, " the intestinal canal is enclosed 

 in a lacupa or rather a veritable sheath taking the place of a 

 dorsal vessel." Claparede adds from his own observations the 

 statement " that a number of the sedentary aanelides present the 

 same peculiarity of having the intestine included in a vascular 

 sheath playing the part of a dorsal vessel." In this view the two 

 chief vessels, in figure 1, at the sides of the intestine, are to be 

 regarded as sections of the vascular sheath enclosing the latter. 

 The principal movement observed in the vessels of 3Ianayunkia, 

 consisted in an incessant pumping of blood into those of the two 

 larger tentacles alternating with contraction and partial expulsion 

 of blood from the same. 



The nervous system of Manayunkia I did not attempt to inves- 

 tigate. A well-developed eye occupied the head at the side of the 

 gullet. It exhibited a clear vitreous humor in a choroid cup. No 

 trace of eyes was to be detected in the terminal segment of the 

 body, sucli as exist in Fahricia. 



In several instances in which I have extracted Manayunkia 

 from its tube, a number of 3'oung ones, about half a dozen, have 

 been liberated, from which it appears that the eggs are laid within 

 the tube, there hatched, and the young then retained under the 

 care of the parent until sufficiently developed to be able to care 

 for themselves. 



Figures 8-13, PI. IX, repi-esent an ovum and a series of 3'oung 

 in ditferent stages of development, which were obtained together 

 with others in the same condition from three tubes. 



Th^ ovum, fig. 8, about 0*2 mm. long, obtained with several 

 similar ones from a tube, exhibits a central mass of large, yoYk- 

 cells enclosed by a layer of smaller ones. Fig. 9 represents an 

 em.bi*yo, which accompanied the former. It was motionless and 

 devoid of cilia. The yolk-cells appear J;o have been resolved 

 into a stomachal cavity. The embryo was about the same size 

 as the ovum. Fig. 10 represents a more advanced embryo, from 

 the same tube. It measured 0"265 mm. in length. The intestine 

 indicates a division into eight segments. Fig. 11 is a more 

 advanced stage of development of the worm from another tube. 



