176 KKSEARCHES IN HELMINTHOUK. V AND PARASITOLOGY. 



the latter itself. The condition I did not comprehend until I found 

 an explanation in the following paragraph in Claparede's Recherches 

 sur la structure des Annelidas Sedentaires, Geneva, 1873, page 76 : 

 " M. de Quatrefages has discovered that in certain vSerpuliens," to 

 which family Fabricia and .]/a)iavit)tkia belong, "the inte.stinal 

 canal is enclosed in a lacuna or rather a veritable sheath taking 

 the place of a dorsal vessel. ' ' Claparede adds from his own observa- 

 tions the statement ' ' that a number of the sedentary annelides pre- 

 sent 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 i, at the sides of the intestine, are to be re- 

 garded as sections of the vascular .sheath enclosing the latter. 



The principal movement ob.served in the vessels of Mauayunkia 

 consisted in an ince.ssant 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 Manayioikia I did not attempt to investi- 

 gate. 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 is to be detected in the terminal segment of the body, 

 such as exist in Fabricia. 



In several instances in which I have extracted Manayiuikia from 

 its tube a number of young 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 them- 

 .selves. 



Figures 8-13, plate IX, represent an ovum and a series of joung 

 in different stages of development, which were obtained, together 

 with others in the .same condition, from three tubes. 



The ovum. Fig. 8, about 0.2 mm. long, obtained with several 

 similar ones from a tube, exhibits a central mass of large yolk cells 

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

 which accompanied the former. It was motionless and devoid of 

 cilia. The yolk cells appear to have been resolved into a stomachial 

 cavity. The embryo was about the same size as the ovum. Fig. 10 

 represents a more advanced embryo from the same tube. It mea.s- 

 ures 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. It measured one-third of a milli- 

 meter in length. The body wall and intestine are quite di.stinct, 

 the latter exhibiting eight segments. The tentacular lobes have 



