SOLENOCxASTKES. 7 



continued along the dorsal wall of the pericardium ; consequently it is situated ventrally 

 from the atrium. The blood of the atrium is driven into the ventricle through one 

 large opening, there being no question of two atrio-ventricular openings. The wall of 

 both parts of the heart here also remains thin ; it is strengthened by muscular fibres 

 belonging to the surrounding tissue. The ciliated bauds (" bourrelets cilies" of 

 Pruvot) do not fail, at least not in the distal part of the pericardium (Fig. 22, ch). The 

 relatively very large blood-corpuscles are of a peculiar shape, oblong, more or less 

 pointed corpuscles of various forms. They stain pale red with carmalum and usually 

 have a small round nucleus, which may occur at difterent points, and often obviously 

 protrudes (Fig. 2G, A). Further, there occur in the 1)Iood large round cells with round 

 granular nucleus (Fig. 2G, B). 



The animal is mature ; the gouatis extend to close behind the radula. The eggs 

 are formed on the median walls, the spermatozoa on the dorsal, ventral, and lateral walls. 

 Both the gonads are densely filled with products, more especially the distal part, which is 

 entirely filled with eggs, or rather with generative epithelium. The latter seems to 

 become free in the gonads ; in the pericardium, compact masses of small round cells occur 

 (Fig. 25, A), which are also found on the median walls of the gonads, and which probably 

 belong to the generative epithelium. Amongst these large cells mature eggs arc 

 observed, with granular contents and of various sizes (Fig. 25, B) ; even very large eggs 

 are found, though they are of rare occurrence. Such eggs are often surrounded by the 

 small cells of the generative epithelium, enveloping them like a follicle. Further, 

 numerous spindle-shaped cells occur, the extremities of which are more transparent and 

 stain less obviously (Fig. 25, C). Whether there exists any connection between the 

 round eggs and the spindle-shaped cells cannot be decided, any more than we can follow 

 the further development of the eggs. Full-grown eggs occur sporadically ; they are 

 large and round, finely granular, with round nucleus. Amongst the ripening eggs 

 there are always found numerous extremely small globules, the significance of which is 

 perfectly unknown to me. Besides the female genital products, numerous spermatozoids 

 occur in the pericardium (Fig. 25, D). 



The cloacal ducts are not in any way remarkable (Figs. 21-23, cd). They leave 

 the pericardium as wide tubes with ciliated epithelium of irregular height, the inner 

 surface being consequently undulating. First they take a proximal course ; afterwards 

 they bend and run distally, becoming gradually broader and having a more glandular 

 epithelium, which produces a granular secretion. The state of preservation is not 

 such as to enable us to decide whether the structure is similar to that of 

 other forms, viz., glandular cells, alternating with supporting ones. The two ducts 

 unite into a broad praecloacal organ (Fig. 22, po). Each cloacal duct bears, at 

 the point where it bends proximally, a spacious pouch, placed on a short stalk, 

 which I believe to be a receptaculum seminis ; in both of them numerous 

 spermatozoids occur. 



Now it remains to be decided to what form this new species, for which I propose 



