490 ME. R. H. BURNE ON THE 



series the lateral parts of the dorsal lip of the anus extend back- 

 wards some little distance, forming a short but prominent lateral 

 ridge ; and in the dorsal mid-line another prominent ridge is 

 formed by the inpushing of the ureters on their way to open on 

 the urinary papilla. Behind the papilla the ridge is continued 

 on, though diminished in size, to the posterior limit of the 

 cloaca. 



The intestine in Myxine is suspended by a dorsal mesentery, 

 continuous to within some 6 or 7 mm. of the posterior extremity of 

 the body-cavity (PI. 32. fig. 1, mes^ ; on its ventral aspect it is free, 

 but at a point 10 mm. in front of the anus it meets the ventral 

 body-wall, within which it becomes gradually embedded as it 

 bends downward towards the anus : in consequence the posterior 

 end of the body-cavity becomes rapidly constricted and confined 

 more and more to the dorsal surface of the intestine, until at a 

 point directly above the anus it is entirely dorsal in position, and 

 opens by a single pore of 1'2 mm. breadth into the cloaca (fig. 1, 

 p.y.). The peritoneal lining of the body-cavity becomes thicker 

 and closer in texture as the pore is approached, till round the 

 actual orifice of the pore it forms a stout band (fig. l,fh.hd.) of 

 white fibrous tissue extremely rich in small round or pointed 

 cells. Just before the anal opening is reached a gland (fig. 1, 

 sl.gl.) makes its appearance in its upper lip, and as we pass back- 

 ward gradually extends upward on either side into the lateral 

 walls of the genital pore, and finally forms a complete circle by 

 meeting in the dorsal mid-line. The chief part of the gland is 

 situated iu the dorsal lip of the anus and lateral walls of the 

 pore, and is formed of several lobes or divisions separated one 

 from the other by strands of connective tissue, from which yet 

 finer strands are given ofii" that subdivide the lobes into smaller 

 compartments or lobules. Each lobule contains one or more 

 spider-cells, and now and again one of the peculiar "thread-cells " 

 characteristic of the lateral slime-glands, though the number 

 of these is con:iparatively limited. The lobes have the form of 

 flattened cones lying side by side with their apices directed for- 

 ward ; the bases of the cones are open, and so placed that they 

 form a semicircle of openings round the ventral and lateral parts 

 of the posterior margin of the pore ; the extension of the gland 

 upon the dorsal wall of the pore has the form of open glandular 

 grooves. The openings of the gland correspond to the grooves 

 between the upper series of cloacal ridges mentioned previously, 



