214 



smaller, sometimes extremely small pores. A cryptocyst may be found partly in 

 the shape of a semi-circular or semi-elliptical calcareous lamina, which from the 

 proximal margin of the primary aperture extends some way down the inner sur- 

 face of the frontal area, partly within the above mentioned fenestrse. No mar- 

 ginal spines but sometimes short, acropetalous, adoral spines and more or less 

 developed bilaminate spines. The aperture has a more or less strongly chitinized 

 compound operculum, and the distal wall, consisting of a horizontal basal and 

 an obliquely ascending frontal part, as well as the lateral walls, have a larger or 

 smaller number of small, scattered, single-pored rosette-plates. The zooecia are 

 connected with a number of lateral chambers, most often kenozocecia, frequently 

 to a certain extent uncalcified, the typical number of which is four on each side. 

 The second chamber (reckoned from the distal end of the zocecium) is however 

 in a greater or smaller number of zooecia developed into an aviciilarium. The 

 ocecia, usually situated on gonozooecia of more or less peculiar structure, are 

 endozooecial and may be covered either by ordinary zocecia or by kenozocecia. 



The free, highly branched colonies furnished with radical fibres, the zooecia 

 of which are all turned in the same direction, are jointed, consisting of internodes 

 which may contain 1 — 3 zooecia. Most frequently internodes with one and inter- 

 nodes with two zooecia appear in the same colony, alternating in different ways. 



The most peculiar character in this very natural and very distinctly defined 

 family is the presence of the above mentioned lateral chambers. Waters* 

 has called the one, which in a greater or smaller number of zooecia is devel- 

 oped into an avicularium, the »avicularian chamber* and the two contiguous 

 ones the »supra-avicularian« and the »infra-avicularian chamber*, while he calls 

 the proximal one, which is independent of the avicularium, the »pedal chamber*. 

 However the name of avicularian chambeii cannot very well be applied as a spe- 

 cial denomination of the above mentioned chamber, as it must be used in the 

 ordinary sense of the word, i. e. as the name of the chamber in all avicularia, 

 nor can it properly be applied with respect to the zooecia in which this chamber 

 is not developed into an avicularium. For this reason I propose to call these 

 three chambers the »scapular«, the »supra-scapular« and the » infra-scapular « 

 chambers. Each lateral wall of a zocecium in connection with the lateral chambers 

 mentioned has generally two separate groups of rosette-plates, a distal and a 

 proximal, the number of plates in which most frequently varies between 10 and 4 

 but sometimes may be only one. In the genus Hincksiella the proximal group is 

 wanting and the distal one represented by 1—2 rosette-plates. In the species of 



1 J07, p. 83, 



