492 ME. E. n. BTJENE ON THE 



thelium, while tlie rest of tlie cloaca witL. the anal and ureteric 

 openings has much the same form and proportions as in Myxine, 

 we must consider that this region in Bdellostoma is in a less simple 

 and generalized condition than in Myxine, and that the divisioa 

 o£ the pore is most likely a secondary modification brought about 

 by its apposition to the edge of the mesentery in consequence of 

 the forward extension of the cloaca, — in fact an incident in the 

 history of the pore after, and not before, its assumption of the 

 single condition ; so that although, to all intents and purposes, 

 Bdellostoma has two genital pores, morphologically it, like Myxine, 

 has but one. The peritoneal thickening that surrounds the pore is 

 well-developed and seems, so far as tlie imperfect preservation o 

 the material at my disposal shows, to be more fibrous and less 

 cellular than in Myxine; it is thicker above and below than at 

 the extreme lateral points, giving to the pore in its normal state 

 the form of a long narrow slit with its dorsal and ventral surfaces 

 closely apposed. 



The portion of the cloaca between pore and anus (fig. 2, cl.ex.) 

 is raised into a number of longitudinal laminae arranged some- 

 what as follows : — In the dorsal mid-line there is a very conspicuous 

 single lamiua, followed on either side after a small smooth space 

 by a group of about 12 laminae of slightly smaller size, arranged 

 close side by side, parallel one to the other ; upon the ventral wall 

 the laminae have a similar arrangement, though none of them are 

 quite so strongly marked. The space between the laminae is filled 

 with a quantity of sticky slime, which is seen under the micro- 

 scope to correspond to the secretion of the lateral slime-glands. 

 The failure of transverse sections to show any communica- 

 tion between this part of the cloaca and the lateral slime- 

 glands, in addition to the presence of a slime-gland round the 

 abdominal pore in Myxine, would lead one to expect that the 

 laminae are the seat of the secretion of the slime. Unfortunately 

 the state of preservation prevents my saying anything very 

 definite upon their histology ; but the following points seem 

 fairly clear and, so far as they go, support the notion that this 

 region of the cloaca is a slime-gland. The laminae are supported 

 by a central sheet of connective tissue, from which are given off 

 subsidiary branches that now and again anastomose with one 

 another ; the connective-tissue support is clothed by a deep 

 epithelium, often broken up by finer anastomosing strands of 

 connective tissue into round glandular-looking follicles : whether 



