64 SUMMARY OF CURRENT RESEARCHES RELATING TO 



blastidia) are developed, comparable with those which we find in 

 Eudendrium. Professor du Plessis would place the family of Clado- 

 corynidte immediately after the Corynidae (of Allman). 



Porifera. 



Sponges from Naples.* — Dr. C. Keller describes and figures on 

 two beautiful plates four hitherto unknown sponges from the Gulf of 

 Naples. Bhizaxinella n. g. is allied to Axinella 0. Schmidt. The 

 proximal (basal) end of R. elavigera u. sj). is rounded, but is fixed in 

 its place by a tuft of root-like processes (Wurzehchopf). The cylin- 

 drical, somewhat prolonged, coenosarc has itself no canal-system, is 

 dichotomously branched, and ends distally in a small number of 

 club-shaped, slightly constricted zooids, each with its terminal 

 osculum. The young zooids are spheroidal, without oscula. In a 

 specimen about six inches high, with six zooids, one of these showed 

 two oscula. — Cribrella labiata n. sp. is remarkable for its sharply limited 

 pore-areas, whose elevated protrusible lips, when the sponge is 

 disturbed, can almost be brought into contact. — Tuherella n. g. 

 resembles Tethya, but has no stellate spicules. T. tethyoides n. sp. 

 is curiously like Tethya lyncurium, and obviously ditfers in colour 

 (both of its interior and exterior), as well as in form, from T. papillata 

 n. sp. 



In a supplement (pp. 280-282) to the preceding paper, 0. Schmidt 

 briefly describes, from the same region, StelleUa carhonaria, S. fihulifera, 

 and Tetliyophana silifica ; the last of which is so close to Tuber ella 

 teihyoliles of Keller, that it might be placed in the same genus. Two 

 other " new " Neapolitan sponges (Plicatella villosa and PhaJcellia 

 plicata) have been placed in the museum of the station by 0. Schmidt, 

 who also notes two interesting forms from Marseilles allied to or 

 identical with Keller's JRJiiznxinella. 



Both Keller and Schmidt show that the sponge-fauna of Naples, 

 while nearly related to that of the Adriatic, is further enriched by 

 the presence of Atlantic species or genera. 



New Group of Siliceous Sponges— the Plakinidse.t — In his ninth 

 contribution Professor F. E. Schulze deals with the lately discovered 

 forms which he groups under the head of the Plakinidfe, and makes 

 also some important remarks on the general morphological con- 

 clusions to which he has been led by the study of the development of 

 Plnkina monoloplm. 



In a simple saccular stage of development he detects three distinct 

 concentrically disposed layers of tissue, which may well be regarded 

 as ectoderm, mesoderm, and endoderm. Now arises the question, 

 what parts arise from these three layers ? Ganin, who has recognized 

 a similar disposition in a Spongilla, thinks that the endoderm of the 

 larva forms the thin unilaminate investment of the inner surface of all 

 the internal cavities (the " body-cavity " excepted), as well as the 

 outer surface of the various mesodermal septa. The endoderm only 



* Arch. Mikr. Anat., xviii. (1880) pp. 271-82 (2 pis.), 

 t Zeitschr. wiss. Zool., xxxiv. (1880) pp. 407-51 (3 pis.). 



