ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 297 



but the whole story is too complex to be followed without the diagrams 

 and schemata. Moreover, besides the development due to simultaneous 

 epicardio-rectal and epicardio-cesophageal budding, there is another mode 

 in which the budding is exclusively epicardio-rectal. 



The Genus Octacnemus. * — W. E. Ritter gives an interesting 

 account of Octacnemus, based upon several specimens dredged by the 

 U.S. Fish Commission steamer ' Albatross.' He is able, by means of his 

 study of this fresh supply of material, to correct and supplement some 

 of the statements of Moseley and Herdman, and to give a revised dia- 

 gnosis of the genus and of the species 0. herdmani. Undoubtedly the 

 most interesting feature is the branchial sac, which is greatly modified. 

 It is situated within the visceral mass, is functionless as a respiratory 

 organ, but effective as regards nutrition. The stigmata are few, irregu- 

 lar in size, form, and distribution ; the dorsal lamina is very short, in 

 the form of two low ridges ; the endostyle is likewise short and broad. 



Embryology of Pyrosoma. f — A. Korotneff describes the egg and a 

 series of stages in the early development of Pyrosoma. The egg is 

 meroblastic ; at the 32-celled stage the segmentation becomes equatorial 

 (cf. bony fishes), and gives rise to a many-layered disk. The similarity 

 and parallelism suggest homology with bony fishes, but whether the 

 resemblance is due to mechanical principles, or to a remote relationship, 

 is an open question. The occurrence of a syncytium, which forms a 

 common bed for the blastoderm disk, and which probably arises by an 

 incomplete division of the blastomeres, perhaps points to an ancestry for 

 Pyrosoma amongst phylogenetically higher forms. Regarding the bud- 

 ding of the ascidiozooids, the author is at one with Salensky. 



INVERTEBRATA. 

 Mollusca. 



0, Gastropoda. 



Salivary Glands of Snail.} — Pacaut and P. Vigier point out that 

 the saliva of Helix pomatia results from the mixture of the secretion of 

 the two large salivary glands and that of two other organs discovered by 

 Nalepa in 1883, but apparently overlooked since, unless by Amaudrut 

 (1808). 



Nalepa's glands lie symmetrically in the wall of the buccal mass, and 

 consist of a large number of long-stalked, unicellular glands, which 

 open directly and separately into the efferent canals of the salivary 

 glands. The large salivary glands consist of aggregates of unicellular 

 glands imbedded in parenchyma. Both the true salivary glands and 

 Nalepa's glands must be regarded as due to the local differentiation of 

 the same salivary canal, or epithelial invagination. 



Habits of Acera bullata.§ — R. Legendre describes three modes of 

 locomotion — creeping on the floor, the flight-like swimming, and (on 



* Bull. Mus. Compar. Zool. Harvard, xlvi. (1906) pp. 233-52 (3 pis.). 



f MT. Zool. Stat. Neapel, xvii. (1905) pp. 295-311 (3 pis., 4 figs.). 



j Comptes Rendus, cxlii. (1906) pp. 412-14. 



§ Arch. Zool. Exper., iv. (1905) Notes et Revue, No. 1, pp. vi.-xiv. (5 figs.). 



