ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 171 



Larval Stages of Cyclostoma elegans.* ■ — C. Barbieri gives an 

 account of the larvae of this common terrestrial Prosobranch. There is 

 a well developed velar region, without cilia, covered by a layer of 

 vacuolated epithelial cells. There are two vitelline sacs, right and left, 

 the latter the larger. Both are composed of vacuolated cells. The 

 liver develops in the right vitelline sac and in the proximal portion of 

 the left. The more differentiated part of the left vitelline sac atrophies. 

 A considerable tract of the oesophagus consists solely of vacuolated cells. 

 The kidney and the pericardium develop from a common rudiment, 

 and the heart arises as an introflexion of the pericardial wall. At an 

 early stage the pedal gland is formed, and has two distinct ducts and 

 openings, but the proximal parts of the ducts afterwards coalesce. The 

 supra-pedal gland is formed much later and independently of the pedal 

 srland. There are folds on the dorsal surface of the mantle which mav 

 be regarded as a rudimentary branchia. 



Orthogenesis in Gastropods.! — Amadeus W. Grabau discusses the 

 occurrence of orthogenetic variation, i.e. progressive variation along 

 definite and determinate lines, in various Gastropod types, such as 

 Fulgur and Melania. The Melanias, to which he refers in most detail, 

 form a group of highly " accelerated " Gastropods in which the spines, 

 a specialised feature, appearing late in the phylogeny of most Gastropods, 

 have become a dominant character, appearing before the ribs have 

 disappeared. Many " phylogerontic " members of this group, forming 

 terminals of genetic series, retain their ornamentation only in the young, 

 the adults becoming smooth. In several lines extreme accentuation of 

 certain characters at the expense of others has resulted in grotesque 

 forms. All the characters, however, appear and disappear in a regular 

 progressive manner both in ontogeny and in phylogeny. The Melanias 

 therefore constitute an excellent group from which illustrations of ortho- 

 ontogenesis and ortho-phylogenesis may be obtained. 



Minute Structure of Ganglion-cells of Tethys leporina.ij:— Hugo 

 Merton describes the canalicular system within the ganglion-cells 

 of Tethys. There is a genuine network which penetrates the entire 

 endoplasm, and forms a meshwork around the nucleus. The close 

 relations between the chromophilous substance and the network point to 

 a reciprocal interaction between the two, which is probably of import- 

 ance in the metabolism of the ganglion-cell. 



Gastropods of the Magellan Province^ — H. Strebel completes his 

 survey which includes 236 species and varieties, of which 209 are marine. 

 In the present instalment he deals with Acmcea, Fissurella, Patinella, 

 Siphonaria, Stephanoda, etc. The characteristic species are Trophon 

 geversianus, laciniatus and decolor, Voluta ancilla, Photinula violacea, 

 Patinella mar/ellanica, Nacella cymbularia, Fissurella alba, Euthria 

 plumbea and magellanica. 



* Zool. Anzeig., xxxii. (1907) pp. 257-84 (21 figs.). 



+ Amer. Naturalist, xli. (1907) pp. 607-46 (3 pis.). 



% Zeitschr. Wiss. Zool., lxxxviii. (1907) pp. 327-57 (2 pis.). 



§ Zool. Jahrb., xxv. (1907) pp. 79-196 (8 pis. and 6 figs.). 



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