349 



lateral wall are provided with a row of small uniporous rosette-plates, of which 

 those of the distal wall are often separated by small calcareous thickenings, which 

 can be seen through the basal wall of the colony. 



This family is very rich in species and the majority of the species have been 

 described by Busk, Mac Gillivray, Ortmann and others under the name 

 Cellepora, which generic name however with them also embraces the species of 

 the family Celleporiclae. In his work on the Brj'ozoa of the Challenger Busk 

 divides the genus Cellepora sens. ext. into two groups, mainly after the form of 

 the aperture and the structure of the operculum, and with exception of Cellepora 

 rudis which belongs to our new genus Siniopelta all the species which he refers 

 to the group § I belong to the family Holoporellidae. From 1895 Mac Gillivray 

 uses the name Cellepora exclusively for the species we have referred to this new 

 family and forms a new name Schismopora for the species of the family Celle- 

 poridae. Since however Cellepora ranudosa L. is the typical species for the genus 

 Cellepora, Mac Gilliv ray's use of this generic name is quite incorrect. As ex- 

 plained above, some few species are described under the generic names Scliizo- 

 porella, Monoporella and Discopora. 



A detailed, comparative investigation of the separate species will possibly make 

 it necessary to set up several genera, but provisionally we must refer them all 

 to a single genus. 



Holoporella Waters'. 



Cellepora Busk, Hincks pari.; Cellepora Mac Gilliv. (after 1895). 



Monoporella Hincks part.; Schizoporella Hincks part.; 



Discopora Sniitl part. 



The two families Celleporiclae and Holoporellidae, the species of which compose 

 the main part of the old family, Celleporidae, seem in all essential characters to 

 be well-separated in spite of their great resemblance in appearance, due in part 

 to the superficial budding aiul the more or less erect zoa'cia, in part to the 

 strong armature which in both families has a very similar character. This 

 armature appears in fact in a double form; we have in the first place a 

 great development of avicularia, which occur not only on the single zooecia but 

 as a rule also scattered over the surface of the colony as independent avicularia. 

 In the second place we find in a great number of species the colony bristling 

 with rostra or pointed projections, which sometimes belong to the zooccia, some- 

 times to the avicularia. The strong armature shown by these two families might 



' IK) a, p. 159. 



