44 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Caelentera. 



Division of Protohydra leuckarti.* — W. M. Aders describes, what 

 Greeff and Chun have reported, the transverse division of this very 

 simple hydroid polyp. Besides the longitudinal muscular elements de- 

 scribed by Greeff and Chun, there are fine annular muscular elements. 



Transverse division in Hydra seems to be very rare. No budding 

 is known in Protohydra. Budding is usual in Microhydra, but no 

 division has been seen. 



Observations and Experiments on Clava squamata.t — A. Billard 

 describes the degeneration and loss of tentacles in this hydroid when 

 sexual maturity is reached. But a similar degeneration was also seen in 

 young immature forms. Agassiz has noted a similar degeneration in 

 sexually mature specimens of Syncoryne. 



Billard has made a number of successful grafting experiments with 

 Clava, and describes the somewhat slight regenerative capacity which 

 this hydroid exhibits. 



Minute Structure of Syncoryne sarsii.J — E. Citron has made a 

 histological study of this Tubularian, and describes minutely the covering, 

 interstitial, stinging, ganglion, and sensory cells of the ectoderm ; the 

 nutritive, tentacular, glandular, and stinging-cells of the endoderm ; 

 the supporting lamella, and so on. 



Hydroids of Pacific Coast of North America.§ — H. B. Torrey 

 makes a systematic report on these. Some of his general notes are of 

 much interest, e.g. on the frequency of skeletal modifications due to 

 environmental influences ; and there is much pertinent cecological 

 material throughout the paper. In connection with Corymorpha palma, 

 the author describes phenomena of orientation, regeneration, &c. ; in 

 some other cases he has brief notes on the development. The- keynote 

 of the paper is that even good systematic work requires prolonged 

 study of the living animals. 



Adult Pelagic Cerianthid.|| — Ch. Gravier communicates an inter- 

 esting note on some adult pelagic Cerianthids captured by L. Diguet in 

 the Gulf of California. They were swimming near the surface in con- 

 siderable numbers, and the reproductive elements were Very nearly ripe. 

 Young pelagic stages {Arachnactis, &c.) of Cerianthids are familiar, but 

 this is the first observation of an adult pelagic form. The mesenteries 

 were rather " biseptal " than " quatroseptal," thus differing from known 

 Cerianthids. The larva described by E. van Beneden as Dactylactis seems 

 nearest the new form. 



Actiniaria of the Olga Expedition. IT — 0. Carlgren reports on an 

 Arctic collection of eight species previously described. With one ex- 



* Zool. Anzeig., xxvi. (1902) pp. 33-9 (11 figs.), 

 t Bull. Mus. Hist. Nat. Paris, 1902, pp. 345-9. 

 t Arch. Naturges., lxviii. (19u2) pp 1-26 (2 pis.). 



§ Publications Univ. California (Zoology), i. (1902) pp. 1-104 (11 pis.). 

 I| Comptes Eendus, cxxxv. (1902) pp. 591-3. 



Tf Zool. Ergebn. einer Untersuchuugsfahi t des Deutsch. Seefischerei Vert-ins nacb, 

 der Bareninsel u. Westspitzbergen, ii. Teil. (1902) pp. 31-56 (1 pi. and 10 figs.). 



