ZOOLOGY AND BOTANY, MICUOSCOI'Y, ETC. 55 



formed from ]\Iarch to June, buds are formed from July to October, and 

 ephyrje in December or at the end of November — three modes of repro- 

 duction in a year. After the formation of ephyrte there is a resting 

 period in January and February. The tliree modes or periods may over- 

 lap considerably. The cyst-formation is a sort of ptedogenesis, which 

 ensures the preservation of the species after a long latent state. 



Kerunia and Hydractinia.* — E. Fraas discusses the curious fossil 

 from the Fay urn known a-; Kerunia cornuta, which Mayer- Eymar 

 regarded as the phragmacoue of a Cephalopod, which others have shown 

 to be allied to Hijdractinin. There is no evidence of Cephalopod struc- 

 ture, but there appears to be a Gastropod shell in the core of the 

 Kerunia. Fraas describes the recent Hijdractinia cakarea Carter, from 

 the Fiji Islands. There is a Serpula-^hdl coiled in the interior. Within 

 the Serpula tube there are residues of the moult of a hermit-crab. Then 

 there is the encrustation of Hydractinia on the outside. This throws 

 light on the nature of Kerunia. 



Eleutheria.t — Hermann Miiller discusses this genus of Cra-^pedote 

 medusoids. He upholds the distinctness of Eleutheria dichotoma and 

 E. claparedii. He describes in the latter the appearance of the male 

 ani female gonads around the mmubrium. He found no evidence of 

 a dorsal brood-chamber in E. claparedii. In E. dichotoma the umbrellar 

 cavity is reduced to a minimum, and the brood-cavity is, as Hartlaub 

 indicated, nothing jnore than a dorsal continuation of the sulmmbrellar 

 cavity, which serves for the production of the reproductive elements and 

 the protection of the embryos in their early stages. The production of 

 medusoid buds from the circular canal takes place to the outside in 

 E. dichotoma, and in the umbrellar cavity in E. cla-paredii. The author 

 seeks to amend the definition of the irenus. 



»^ 



Observations and Experiments on Ctenophore Ovum. J — Naohide 

 Yatsu has studied the developing t'^g of Callianira hiaJata and compared 

 it with that of Bero'c, from which it differs in having the third cleavage 

 plane sometimes horizontal or tending to be horizontal, and in having 

 the fourth micromeres budded off from the end-cells. 



If a portion of cytoplasm is removed from the egg before the com- 

 mencement of the first cleavage, the nucleated portions cleave like an 

 intact egg. If the Qg^ be split into two during the first cleavage, each 

 nucleated portion always exhibits half-cleavage, as in isolated blastomeres 

 of the 2-cell stage. If the egg be cut along any plane into nucleated 

 and non-nucleated parts during the first cleavage, the former divides 

 like a whole agg, forming micromeres in the normal way. 



End-cells are more variable in size than middle cells in eggs that 

 have been operated on. The size of micromeres depends chiefly upon 

 that of the fragments producing them. The size of the micromeres 

 from the end-cell is not proportional to that of its macromere in operated 

 eggs. Macromeres seem to have a tendency to keep their proper size. 



♦ Verb. ZojI. Bot Ges. Wien, Ixi. (1911) pp. 70-7 (5 figs ). 



+ Arch. Naturges., Ixxvii. (1911) pp. 159-69 (1 pi.). 



; Annot. Zool. Japon., vii. (1911) pp. 333-46 (25 figs.). 



