38 BULLETIN OF THE 



The basement membrane is a product of the hypoderniis. It is struc- 

 tureless. 



The pigment is intercellular, occurring in the form of scattered 

 granules. 



The pseudocoelar spaces of the mesenchyma are intercellular in ori- 

 gin, and sagittal muscles are directly continuous with processes of the 

 mesenchyma cells. 



The nervous system consists of a deeper and a superficial portion ; a 

 marginal nerve indirectly connects the two. The condition in Phagocata 

 may be intermediate between that of Gunda and lihynchodesmus. 



The brain presents two commissures, an anterior and a posterior one, 

 uniting the longitudinal nerve trunks. The so called " Substanzinseln " 

 are intrusive connective tissue. 



The testes give rise to tubular outgrowths, the vasa efferentia. The 

 vasa deferentia have terminal enlargements and function as vesioulse 

 seminales. 



The yolk glands arise by cell proliferation from two cell masses, the 

 parovaria, which are in immediate contact with the ovaries. The intimate 

 connection of the parovaria with the ovaries indicates the differentiation 

 of the ovary and vitellarium from a common gland. 



The so called uterus is not only a gland ; it is a place in which the sex- 

 ual elements are brought together, and where fertilization consequently 

 takes place. 



Cambridge, August, 1890. 



It was not until this paper had gone to press that I had access to the 

 recent work of Bohmig ('91) on Rhabdocoeles. It was then too late for 

 any detailed review. I am gratified to observe, however, that he has 

 arrived at conclusions from his studies of Rhabdocceles which agree in 

 many points with those which I have expressed in the foregoing paper, 

 especially in his statements as to the fate and significance of rhabditi. 



