Dr. F. A. Bather — Notes on Yunnan Cystidea. 323 



Williams has just claimed to Lave detected it in Agelacrinus itself), 

 the Caryocrinidae, and Malocystis; also that there is a gonopore, 

 probably or certainly with a hydropore also, in Caryocystis, 

 Cryptocrinus, Cheirocrinus, Orocystis, Sphaeronis, and Sphaerocystis 

 (here Schuchert, 1904, calls it the hydropore, although he acknow- 

 ledges another opening as " madreporite "). In a word, it is no 

 longer safe to ascribe the apparent absence of these openings from 

 any cystid to anything but our ignorance and the extreme difficulty 

 of dispelling it. Thus the argument from other genera, so far from 

 supporting the views of Carpenter, points to the presence of both 

 gonopore and hydropore in all species of Megaeystis. 



Lastly we come to the evidence of the British Museum specimens. 

 These, even when they are closely similar in all other respects, do, 

 it is true, present some interesting variations in the shape and 

 distribution of these openings, but both openings can nearly always 

 be detected. 



£7<$4 o E 7677 E 7^37 



FlG. 31. — Hydropore-sutures in Megaeystis. 

 These all occur in specimens of M. gorbyi character, and show the replacement 

 of the hydropore-slit by a sinuous suture between the posterior Adorals I. 

 x 10 diam. 



The Hydropore is plainly seen in ten specimens, and faintly 

 suggested in about six more. In the remainder it has been obscured 

 by crushing or by encrusting organisms, or the plates are absent. 

 Normally it appears as a narrow groove or a dark line, indicating 

 a slit, crossing the suture beween the two posterior Adorals I at 

 right angles, just outside the peristome rim. In E 16168, identified 

 as H. scitulus by S. A. Miller, the length of the slit is 1*2 mm., and 

 this seems to be above the average. In E 7638 the slit seems to be 

 continued on the right into a sinuous suture, which reaches the 

 right posterior facetted plate and so bisects the right posterior Ad 1. 

 Sometimes the slit is on an eminence, as in E 7633, ? E 7635, 

 E 7642. All these specimens are, like M. scitulus, of M. gorbyi 

 character. In E 7673, a strongly pustulate form, the position of the 

 hydropore seems indicated by a rather irregular rim (antea, fig. 29). 



In a few of the specimens where the hydropore is less plain, the 

 existence of some such structure is suggested by a remarkable 

 sinuosity of the suture (fig. 31). In E 7636, a dark spot indicates 

 the actual pore, and the suture just here makes a slight bend. In 

 E 7644 the suture is sharply bent where it crosses the hydropore- 

 slit. In E 7640 no opening can be detected, but in the middle of 

 its course the suture takes a sharp semicircular curve to the left, and 



