418 DR F. A. BATHER. 



one might expect to find at its distal end a parietal pore (? gonopore), perhaps 

 combined with a hydropore. Careful examination, however, has convinced me that 

 there is no opening through the marginals of the frame except that breach on the 

 obverse where the vent lies. It is therefore possible that the axial tracts of the various 

 systems concerned, after passing up the strut, proceeded up the marginals on the front 

 of the leg, and that the openings of the water- vascular and generative systems were 

 either through the loose integument at the base of the " tongue/' or involved with the 

 anus in a cloaca. Since careful search has failed to detect any independent opening, 

 the latter hypothesis is the more probable. Extensions of, at any rate, the nervous and 

 vascular systems doubtless passed down the stem-lumen, finding their way between the 

 muscles and sinews of the proximal and median regions (§ 240), and therefore lying 

 in the flutings of the median and distal lumen. Whether there is any trace of quinque- 

 radiate symmetry in those flutings, is a question obvious to ask, but at present impossible 

 to answer. 



Affinities of Cothurnocystis. 



§ 245. The absence of any rhombs or pores excludes reference to the Rhombifera 

 and Diploporita ; and the structure of the stem, in its proximal region at least, 

 indicates that the genus belongs to the Heterostelea. But among the Heterostelea 

 there is no known genus with which comparison is at once obvious. 



It is, of course, out of the question to consider any of the specialised Silurian 

 genera, such as Placocystis ; nor is it profitable to seek a relationship with the 

 brachioliferous forms allied to Dendrocystis. 



§ 246. Some comparison with Trochocystis is possible, for that genus is the least 

 specialised of the Anomalocystid series, and its occurrence in the Cambrian would at 

 any rate permit it to be an ancestor of the late Ordovician Cothurnocystis. Obvious 

 points of resemblance are presented by its theca, consisting of a plated integument 

 stretched within a frame of marginals. The plating is far coarser and more regular 

 than in Cothurnocystis, but it is important to notice that the number of marginals is 

 approximately the same, not less than 10 and not more than 12, since this is a 

 character of less physiological value and therefore less likely to be modified by any 

 change of habit. Further, the marginal near the presumed vent is incomplete or 

 excavate on the side of the vent, just as are marginals 11 and 12 in Cothurnocystis. 



§ 247. It might be supposed that the peculiar process shown above the vent in 

 Barrande, pi. 3, ff". 13, 14, was of a nature similiar to the tongue process in 

 Cothurnocystis, and, like it, intended to divert the faecal current from the intake. 

 Examination of the original specimen, however, reveals the process as nothing more 

 than the hypostone of a Paradoxides, a trilobite not uncommon in the same bed. 

 Whether there was anything in the nature of a valve closing the anus, as Dr Jaekel 

 states (1901, p. 669), or any plate diverting its stream, is more than I am at present 

 prepared to affirm or deny. 



T 



