42 HENRY H. LANE. 



V. GROSS ANATOMY. 



For the sake of clearness the following terms will be used in 

 the sense here given : 



Oviduct the single duct leading from the ovary to the uro- 

 genital pore. Ovisac the forward continuation of the oviduct 

 which covers the ovary. Ovary the structure containing the 

 eggs. Stroma the supporting tissues of the ovary itself. 



The term ovary is also used in a general way to include the 

 ovisac and the ovarian structures proper. The context in every 

 case will determine what is meant. 



In Liicifitga and Stygicola the ovary is enclosed between two 

 layers of peritoneum above the posterior portion of the alimentary 

 canal. It may extend so far forward as to lie in part even beside 

 the stomach. 



The ovary has a bilateral arrangement. Externally it is a 

 Y-shaped, bifurcated, subcylindrical organ, whose greatest diam- 

 eter is immediately posterior to the point at which the division 

 begins (Fig. i). The two horns lie on the right and left sides 

 respectively and may enclose between them the posterior portion 

 of the stomach. Interiorly the stem of the Y is divided by a 

 median partition with which the ovarian structures proper are 

 associated and which extends to near the oviduct, though here 

 only the portion attached to the ventral wall is found (Fig. 2). 

 From the tips of the ovarian horns slender though comparatively 

 strong threads of connective tissue, inclosing blood vessels, run for- 

 ward and fasten to the peritoneal walls, thus very securely hold- 

 ing the ovary in position. Dorsally, the ovary is attached to the 

 peritoneal lining of the body cavity by the mesovarium ; ventrally, 

 there is a corresponding attachment, the mesorectum. The ovi- 

 duct, which opens externally at the urogenital pore, increases 

 gradually in size as it approaches the ovary and finally merges 

 into the ovisac, or outer wall of the ovary. 



A somewhat immature specimen shows finely those structures 

 connected with the support of the ovary. In it one sees that 

 each horn is supported by its own fold or lamina of peritoneum ; 

 that these two laminae become united at or near*the point of di- 

 vision of the horns and are continued posteriorly as a single 

 though thicker mesovarium supporting the body of the ovary 



