ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 615 



the Irish Sea in early summer, while a similar micro-flora is present in 

 quantity in some parts of the sea on the west of Scotland (e.g. the Sound 

 of Mull and the sea around Canna, Eigg, etc.) until July, and possibly 

 later. It can scarcely be doubted that the phyto-plankton maximum is 

 found in spring in the Hebrides as in the Irish Sea. But have the July 

 Diatoms remained, or have they reappeared ? 



A survey of numerous gatherings of zoo-plankton shows (1) that 

 localities, in some cases not very far apart, differ very considerably in the 

 nature of their plankton at the same time of year ; and (2) that there is 

 constancy year after year in the nature of the plankton in some localities. 



Moss-fauna of Central America.* — Fr. Heinis reports from dry 

 moss and lichens thirty-eight Rhizopods (including Corycia spinosa sp. n.), 

 eleven Rotifers, and three Tardigrades (including Erkiaiscus siegrisfi 

 sp.n.). 



INVERTEBRATA. 



Mollusca. 



a - Cephalopoda. 



Japanese Cephalopods.t — G. Wulker deals with a collection made 

 by Doflein in Japanese waters. It includes twenty-five species (four 

 new) in eleven genera. The Japanese Cephalopods show most resem- 

 blance to the Indo-Malayan forms, but there is a close similarity also to 

 those of the Mediterranean. The author devotes much attention to the 

 " salivary " glands of the different types. 



7- Gastropoda. 



New Fossil Chiton from Girvan.f — F. R. Cowper Reed describes 

 Helminthochiton thraivensis sp. n., from Starfish Bed (Upper Bala), Gir- 

 van. It has a narrow elongated body, with eight imbricating plates and 

 marginal girdle (?) of spicules. The surface of all the plates is covered 

 with closely set pores, which, as in living forms, probably served for the 

 passage of nerves to superficial sensory structures. The nearest affinities 

 of the Girvan form are with H. (jriffithi Salter. 



5. Lamellibranchiata. 



Artificial Parthenogenesis in Mactra.§ — K. Kostanecki has studied 

 the development induced in the eggs of Mactra by the addition of some 

 potassium chloride solution to the sea-water. The ordinary cleavage 

 does not occur, but the nuclei multiply by multipolar mitosis and ciliated 

 larvas are formed. 



The eggs may give off two polar bodies, or only one, or none. In 

 every case a bipolar segmentation spindle is formed, in the first case from 

 a single ovum-nucleus, in the second case from two ovum-nuclei, in the 



* Rev. Suisse Zool., xix. (1911) pp. 253-66 (1 pi. and 3 figs.). 



f Abh. k. Bayer. Akad. Wiss.. iii. (1910) Supp. Band. i. pp. 1-70 15 pis.). See 

 also Zool. Zentralbl., xvii. (1911) pp. 792-5. 



: Geol. Mag., viii. (1911) pp. 337-9 (1 pi.). 



§ Arch. Mikr. Anat., lxxviii. (1911) Festschrift Waldeyer, 2"- Ant., pp. 1 62 

 (4 pis.). 



