251 



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

 is occupied by two lateral chaml)ers, the proximal of which is the jjcdal, while 

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

 ciuni. Of these the former is of a (piadrangularly 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 bell separating the two large, long, bean-shaped fenestric of the 

 kenozoa^cium, which may sometimes meet on the frontal surface, sometimes be 

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

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

 of which terminates in a number of luliercles 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 kenozocvcium 

 we find an arrow-shaped, mend)ranous chamber, which is sharply pointed fron- 

 tally and deeply indented l)asally and the basal half of which is incompletely 

 divided into two i)y 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-zoci'cial internodes is regular 

 except in the lateral branches, which often spring from a daughter-zoo'cium and 

 which in every other bizoiecial inlernode bear only bi-zoa'cial joints (uj) to ')). 

 I have liowever sometimes seen such a l)ranch completed by a single zoii-cium. 



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

 posal by Dr. Harmer. 



Calpidium ornatum Busk. 

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



pag. 15, PI. XII, XIII. 

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

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

 by about a half, is provided with 5 fenestra? 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 zoa>cia may hide the inner 

 lamina entirely. The elongated aperture has a constriction somewhat |)roximally 

 to the centre, and here we find two robu.st, conical, cylindrical hinge-teeth con- 

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



