224 J- Playfair Mc Murrich, 



to its outer surface being raised into irregulär ridges. Its inner 

 surface was raised into noticeable, but not liig-li folds, for tlie circular 

 musculature. The spliincter seems to liave been imbedded in tlie 

 mesogloea, for just below tlie line of Insertion of the outer tentacles 

 tliere was in tlie column wall a narrow band of wliat seemed to be 

 muscle tissue, enclosed within tlie mesogloea and separated by narrow 

 bands of it from botli the ectoderm and the endoderm. Having- oiily 

 a Single specimen for study and having devoted its distal extremity 

 to transverse sections, I cannot make any statement as to the pattern 

 of the muscle. 



Themesogloea of the tentacles and disc was quite tliin and the pro- 

 cesses for their ectodermal muscles were short and simple; indeed, 

 they were barely perceptible upon the disc. The stomatodaeum was 

 Short, being practically conflned to the dome-like elevation of the 

 disc. It was richly folded longitudinally and the two siphonoglyphs 

 which were present were hardly distinguishable. either in form or 

 structure, from the rest of the stomatodaeal surface. 



There were tAvelve pairs of mesenteries, only six of which were 

 perfect ; two of these were directives. In a section through the upper 

 part of the scapus, cutting the mesenteries a little below the lower 

 edge of the stomatodaeum (Fig. 3), the six perfect pairs alternate 

 regularly with six very small pairs. Throughout the greater part 

 of their breadth the perfect mesenteries are very thin, but bear at 

 the junction of their muscular and reproductive portions a strong 

 circumscribed muscle pennon, of the usual Edwardsian type and con- 

 sisting of almost tweiity long, more or less branched processes. A 

 slightly developed parietal muscle occurs on both the perfect and 

 imperfect mesenteries, it being the only muscle present on the latter. 



On comparing the muscle pennons of the diiferent mesenteries 

 it will be Seen that they vary considerably in their development. 

 Thus the pennons of the pairs situated on either side of the direc- 

 tives marked D in Fig. 3 are noticeably sm aller than those on the 

 majority of the other mesenteries, and, furthermore, the pennon of 

 the individual of each of these pairs which is nearer the directives 

 is niuch weaker than its fellow. Finally, a distinct difference is 

 noticeable in the size of the pennons of the two directive mesenteries 

 marked D'. In a section taken lower down, about the junction of 

 the middle and lower thirds of the scapus, the condition represented 

 in Fig. 4 is seen. The primary pairs are readily distinguishable by 

 their greater breadth, although the secondaries are much broader 



