262 VERA KOEHRING. 



EXPLANATION OF FIGURES. 

 PLATE I. 



FIG. i. (Mag. X c. 85.) Fig. i is a diagrammatic drawing of a young functional 

 spermatheca with part of the pigment sac removed. The diagram is based upon 

 the study of the spermatheca of the 69 mm. female of Fig. 3 and the immature 

 spermatheca of a 71 mm. specimen described in the text. An average of eight 

 tubules would be typical of this stage. The necks bend but slightly posterior 

 and some are anterior in direction. At their convergence the central tubule is 

 extremely large but short, antero-posteriorly, and narrows as it dips into the 

 cloaca. The posterior wall and floor of the spermatheca are densely pigmented 

 and sockets enclose the bulb of each flask tubule. 



FIG. 2. (Mag. X c. 85.) Fig. 2 is a diagrammatic drawing of an older sperma- 

 theca. The sac wall is removed and half of the tubules are shown, bisected to 

 show their contents the coiled spermatozoa in the flask tubules. These tubules 

 lying in the floor of the sac in pigmented sockets bend posteriorly and dorsally to 

 converge into the central tubule. The reservoir formed by this convergence 

 narrows and the duct passes anteriorly through the dorsal part of the sac where 

 it bends to pass into the cloacal wall. The diagram shows this portion of the 

 central tubule anterior to all the flask tubules but in many cases it passes between 

 the two most anterior flask ends. See Fig. 7. (Mag. X c. 85.) 



FIG. 3. (Mag. X 19.) Fig. 3 is a para-sagittal section through the region of 

 the rectum and cloaca of a 69 mm. female to show the orientation of the sperma- 

 theca. The plane of sectioning is not quite true so that the anterior region of this 

 drawing is very nearly median-sagittal showing the nerve cord, notochord, rectum 

 and bladder. The posterior half of the drawing shows the end of the mesonephros, 

 one oviduct, the spermatheca and the cloaca almost obscured by the many folds 

 of its walls. It is to be noted in this figure that the mesonephros does not extend 

 as far posterior as the spermatheca. This may be compared with transverse 

 sections shown in other figures. In some individuals the mesonephros lies dorsal 

 to the spermatheca and in others it ends more anteriorly. It is not certain whether 

 these variations are due to changes or varying lengths in the mesonephros itself 

 or if they might be due to the influence of the spermatheca. 



An "/" placed below a fold separating the oviduct from the lower part of the 

 cloaca is part of the fold represented in Fig. 10, transverse section. 



The spermatheca in this specimen is young, of the type represented in Fig. i. 

 It is higher, dorso-ventrally, than it is long, antero-posteriorly. There are few 

 tubules and the necks of these do not bend posteriorly. Through a median section 

 the central tubule is large as in Fig. i, but this section is through one side of it. 

 The flask ends are filled with spermatozoa and in this section is the tubule described 

 in the text from which the spermatozoa are streaming into the neck. The lining 

 epithelium of these tubules is flat, unlike the delicate columnar cells pictured in 

 the one flask tubule of Fig. 9, or in Fig. 5. 



"ap" on this figure indicates an interesting fact about the mature cloaca that 

 is very puzzling in transverse sections through the region an anterior pouch, 

 although this section is only through the wall of it. The anterior pouch is a ventral 

 region of the cloaca separated from the anterior dorsal region by a band of muscle 

 between the bladder and the cloaca. The region is left blank in the figure and 

 indicated by "m." Ventral dissections of the cloaca did not show this particular 

 and in transverse sections it appeared so startling that its function was not guessed. 



