138 ALEXANDROMENIA AGASSIZI. 



is paired and the eggs are developed along the septum while the spermatozoa 

 arise more externally where the walls are often greatly folded. Posteriorly the 

 halves of the gland narrow greatly and assume the form of comparatively slender 

 canals (Plate 7, fig. 5), which communicate with the pericardium by wide open- 

 ings. Their epithelial lining is apparentlj^ ciliated and is fashioned into several 

 low longitudinal ridges. 



The coelomoducts arise from the postero-lateral borders of the pericardium 

 as comparatively wide canals, which first extend downward and then forward 

 to join the so-called shell gland at the point where the seminal receptacles are 

 located. As usual the shell gland of one side joins the corresponding organ of 

 the other and after narrowing to a slender tube opens into the cloaca in the mid 

 line. 



The walls of the coelomoduct (see Plate 20) in the region of the pericardium 

 are comparatively thin, but one third the distance to the seminal receptacle 

 they become thicker, the cells more slender and the ten to fifteen longitudinal 

 folds more pronounced, a state of affairs which continues to the shell gland. 

 Cilia are certainly present at various points and it is probable that they exist 

 throughout the duct between the pericardial cavity and the seminal receptacle. 

 In the same section small quantities of a glandular secretion are developed having 

 the form of minute granules which show at first a distinctly acid reaction but 

 after their discharge become more or less confluent and alkaline. Minute 

 quantities of spermatozoa are also distributed throughout this same division 

 of the duct. 



In the single specimen examined the seminal receptacle is a small disc- 

 shaped sac attached to the coelomoduct where the inner and outer portions meet. 

 It is wedged between the body musculature and the shell gland and the slit-like 

 lumen contains a few spermatozoa only. The cells composing the walls are 

 comparatively low and are glandular, the clear secretion, small in amount, 

 giving the cytoplasm a vacuolated appearance. 



In this species the shell gland is of enormous size, filling practically all the 

 space between the digestive tract and jiericardium dorsally and the body muscu- 

 lature ventrallj^ and laterally. As figured, Plate 20, each half is penetrated by 

 a duct, of about the diameter of the foregoing section, through which the secre- 

 tion from the surrounding glandular portion makes its way. In the neighbor- 

 hood of the cloaca these ducts emerge from the gland, unite with each other, 

 and forming an S-shaped loop in side view open into the cloaca by a very narrow 

 pore. 



