176 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



those of the follicle eells, very irregular, and iudistinetly bounded. It is eharaeteri.stic that the 

 chromatin is gathered in a coil in the center of the nucleus." 



The nu)uth of the ovary is usually pressed closely against the inner opening of the oviduct, so 

 that the two are functionally continuous. The oviduct lies between the walls of the pallio-visceral 

 ligament and is thus closely attached to the ovary. 



Hallek mentions that in several cases the mouth of the ovary was not in contact with the 

 inner opening of the oviduct, and so opened into the cceloui. 



The posterior half of the oviduct is thin-walled and broad, nmch like a flattened sac. Its 

 walls seem to be glandular, and are quite smooth. The internal opening of the oviduct is often 

 nuich larger than I have shown it in figure 39, which, however, is an accurate representation of 

 the condition of the specimen from which it was drawn. 



The oviduct leads forward and to the right side of the body. About 20 millimeters from its 

 beginning it becomes much narrower, and its walls become thick and raised internally into annular 

 ridges. The width of the posterior portion of the oviduct is 17 millimeters, while that of the 

 anterior poi'tion is I'J millimeters. Shortly anterior to the commencement of the thickening the 

 ovidui't reaches the surface of the body at the line of junction of the mantle and body wall, from 

 which it projects as a large rounded eminence from 7 to 12 millimeters. The projecting portion 

 of the oviduct is ridged externally and presents an appearance which suggests that a portion of 

 the oviduct has been evaginated. The external aperture of the oviduct forms a transverse slit at 

 the end of the projecting portion. The distal portion of the oviduct is evidently glandular and 

 suggests strongly the glandular distal portion of the oviduct of several Dibranchiata. 



Upon the left side of the heart, in the female as well as in the male Nautilus, is a pj'riform 

 sac lying within the pallio-visceral ligament, and in all respects like the pyriform sac of the 

 male. The position of its aperture, upon the left side of the bod}', corresponds to that of the 

 functional oviduct upon the right side. 



The nidamental gland has been described in the section devoted to the pallial complex. We 

 have as yet no proof of the function of this gland. Analogy, however, guides us in giving it 

 this designation. 



The ovary of a half-grown female was a small elongated body, is millimeters in length by 

 t) millimeters in width. It was situated within the genital ligament close to the heart, extending 

 along al)out one-third of the genital ligament. The intestine and stomach were attached directly 

 to the genital ligament above the ovary. The ovary evidently grows backward and upward in 

 the ligament so that when it is mature the ligaments of the intestine and stomach are attached 

 to its surface. 



The ovary opened into the ccelom just back of the heart, and so at a considerable distance 

 from the inner opening of the oviduct. The functional oviduct was scarcely difterent from the 

 P3'riforni sac at this time. The walls of the portion near the external aperture, which later 

 became rugose and greatly thickened, were in this case only slightly ridged and scarcely thickened 

 at all. The oviduct papilla projected very little into the mantle cavity, and was not at all pleated. 



The genital arteries were discovered l)y means of injections by Willey; since then I have 

 been able to trace the arteries in uninjected specimens. They are three in number and arise 

 directly from the heart. They arise close together in a row from the posterior portion of the 

 dorsal surface of the heart. (Text-fig. 10, p. 182.) 



The genital artery is the middle one of the three, and its main trunk passes over the dorsal 

 surface of the gonad. 



The right-hand artery forms the gonaducal artery and goes to the functional genital duct. 

 The left-hand artery is that of pyriform sac, being distributed mainly to this. Upon morphological 

 grounds it should be considered to be the left gonaducal artery. 



Both the gonaducal artery and the artery of the pyriform sac "give off a branch which 

 passes into the perigonadial membrane." (Willey.) 



The further ramifications of the genital artery of the female have already been mentioned. 



Tile pyriform sac was first described by Owen in a female specimen, and given this name by 

 him. Owen did not discover the opening of the sac to the exterior, and was led by its position 



