HISTORICAL REVIEW. 15 



In 1882 Kowalevsky and Marion called in question the work of all pre- 

 ceding authors, claiming that they in every case had wrongly oriented the ani- 

 mals, that the anterior end is in reality posterior and vice versa. Tullberg's 

 lateral glands (portion of the coelomoducts) are accordingly the salivary glands, 

 the penis with its appendages is clearly the radula, the mouth cavity is the 

 rectum, the "egg bag" (pericardium) is the intestinal coecum above the pharynx, 

 the branchia are the buccal cirri and finally the protrusible pharynx is the com- 

 bined uterus and oviducts. 



This paper called forth an immediate rejoinder on the part of Hubrecht, 

 who reviewed the work of the authors in question, and showed that the orienta- 

 tion of the animals in question is correct, and that Kowalevsky and Marion have 

 created confusion worse confounded owing, for one reason at least, to the fact 

 that they had not seen the species under discussion. 



During the next four or five years Kowalevsky and Marion pulilished, 

 either separately or conjointly, several papers preliminary to their chief work 

 which appeared in 1887. In this study the authors describe to a certain extent 

 the habits of five new species of these molluscs collected along the shores of 

 France, and accompany it with a very detailed description of the external 

 and internal anatomy. Some of these last named results are referred to else- 

 where in the present paper. 



In the meantime Selenka ('85) published an account of the gephyrean worms 

 collected by H. M. S. Challenger, and therein briefly described Chaetoderma 

 mililare from the Malay Ai-chipelago, adding the remark that he was unable 

 to give any data that might settle its systematic position. 



In 1888 Hulirecht described a new genus of Solenogastres (Dondersia) 

 taken in the vicinity of Naples. It is a fairly close relative of Proneomenia and 

 Neomenia, and the anatomical characters are accordingly not striking^ differ- 

 ent from those presented in the paper on P. sluiteri. 



In this same year Hansen ('88) made a study of several species of Soleno- 

 gastres long before described bj' Koren and Daniellssen ('77). His researches 

 chiefly concern Neomenia carinata, which is shown more conclusively than be- 

 fore to be similar to P. sluiteri. Chaetoderma nitidulum was found to pass the 

 sex products into the pericardium from whence they pass thi-ough ducts into 

 the anal cavity (Hubrecht) or branchial cavity (Hansen). 



Pruvot ('90) denied the existence of a heart, or jjericardium or dorsal aorta 

 in the Solenogastres. The blood moves in lacunae of which a large one passes 

 dorsally along the mid line propelled by contractions of the body. The paired 



