the species of the genus Onychocella, Biftustra delicatnla, Vinciilaria abyssicola, 

 Steganoporella Smitti, etc. In a later paper' besides a number of new genera, 

 species of the genera Aetea, Microporella, Scriipocellaria, Bicellaria, Cibrilina, Lageni- 

 pora, Schizoporella, Smittia, Mucronella and Retepora are referred by him to the 

 Monodermata, while he classes species of the genera Caberea, Membranipora and 

 Setosella to the Diplodermata. In a third paper however he has altered^ his view 

 of the extent of the Diplodermata, in that he now classes some of the forms 

 which in the earlier papers he placed under the Monodermata to the Diploder- 

 mata, namely, all the families Eiicrateidae, Cellulariidae (= ScrupocellariidaeJ, Bi- 

 cellariidae, Notamiidae, Flustridae, Membraniporidae, Gemellariidae and Farcimina- 

 riidae. While a systematic classification on the basis of the structure of the frontal 

 wall is still found in a work of Canu^ from the year 1900, on the Bryozoa of 

 the Cretaceous period, this classification seems quite given up in a later coopera- 

 tive work by Jullien and Calvet*, which after the death of the first men- 

 tioned writer has been carried on and published by the latter. Calvet-' gives 

 very important information about the structure of the frontal wall in a large 

 work dealing with the structure and development of the ectoproct Bryozoa. Be- 

 sides in Eucratea Lafonti, Membranipora Rosseli and the species of the genus, 

 Cellaria, he has found a double ectocyst in the species examined by himself of 

 the genera Tubiicellaria, Microporella, Chorizopora, Schizoporella, Lepralia, Umbonula, 

 Retepora and Cellepora, consequently in forms which accoi'ding to Julliens 

 examination have a single ectocyst, while he has found a single ectocyst in the 

 examined species of the genera Aetea, Scrupocellaria, Caberea, Bugula, Flustra, and 

 in Membranipora pilosa and Membr. Flemingi. As to those forms which have a 

 double ectocyst, he gives the interesting information that the interspace between 

 the membranous exterior and the calcified interior layer (the Cryptocyst) is every- 

 where covered by epithelium, and moreover contains leucocytes and a mesen- 

 chymatous tissue. Except in the Retepora where the basal wall of the colony also 

 has a double ectocyst, he only finds such an ectocyst on the frontal wall. 



The result of the investigations above-mentioned is, consequently, that we can 

 distinguish between skeletal parts which come into existence inside the covering 

 membrane and independent of this (the Cryptocyst), and those which arise by 

 transformation of the covering membrane. We may call these last-mentioned 

 parts of the skeleton whose frontal surface consequently has no membranous 

 lining (an »epitheca«): the »Gymnocyst«. 



43; " 45; Mia; * 46; ^ pp. 163—168. 



