251 



greater part of the basal surface and of the lateral surfaces of the gonozocecium 

 is occupied by two lateral chambers, the proximal of which is the pedal, while 

 the distal no doubt corresponds to the three distal chambers in an ordinary zoce- 

 cium. Of these the former is of a quadrangularly rounded form and enclosed on 

 its distal as well as on its basal margin by the latter, which is triangularly 

 kidney-shaped. On the basal surface both chambers of the lateral surfaces are 

 separated by a central belt, which increases in breadth frontally and passes into 

 a still broader belt separating the two large, long, bean-shaped fenestra of the 

 kenozooecium, which may sometimes meet on the frontal surface, sometimes be 

 separated by a narrow central belt. Inside each of the two fenestrse the ocecium 

 is provided with a broad belt of closely situated pores, the separating reticulation 

 of which terminates in a number of tubercles and spinous processes and these 

 structures may also be present partly in the marginal portion of the two fenestrse 

 partly along the distal margin of the aperture. On the top of the kenozocecium 

 we find an arrow-shaped, membranous chamber, which is sharply pointed fron- 

 tally and deeply indented basally and the basal half of which is incompletely 

 divided into two by a longitudinal ridge springing from the indentation. The 

 frontal end of the ridge often terminates in a strong process, and on either side 

 of it we find a group of uniporous rosette-plates. 



Form of colony. The alternation of uni- and bi-zocecial internodes is regular 

 except in the lateral branches, which often spring from a daughter-zooecium and 

 which in every other bizocecial internode bear only bi-zooecial joints (up to 5). 

 I have however sometimes seen such a branch completed by a single zooecium. 



Of this species a colony from Tasmania has kindly been placed at my dis- 

 posal by Dr. Harmer. 



Calpidiuin ornatum Busk. 

 Voyage of Rattlesnake, pag. 364, Catalogue of Marine Polyzoa, Cheilostomata, 



pag. 15, PI. XII, XIII. 



(PL XX, figs. 11 a-11 f). 



The zooecia are oval. The sternal area, which is longer than the aperture 

 by about a half, is provided with 5 fenestrse of very different size, viz. two small 

 distal ones, two larger median and one the largest proximal. Inside the sternal 

 area we find an oval cryptocyst lamina, and further each perforation is provided 

 with a well-developed cryptocyst, which in older zooecia may hide the inner 

 lamina entirely. The elongated aperture has a constriction somewhat proximally 

 to the centre, and here we find two robust, conical, cylindrical hinge-teeth con- 

 verging proximally, of which the terminal part only projects freely in the aper- 



