CURRENT LITERATURE. I 23 



a testis (cf. Tergipes capellinii, Trinchese). This arrangement is a further 

 development of the condition which Mazzarelli finds in the Pleurobranchida?,* 

 and in Pelta ( = Runcina), where the ova and spermatozoa arise in separate 

 follicles. 



The author concludes that the Oxynoeitkv represent the most primitive 

 Ascoglossa, derived phylogenetically from the more primitive Tectibranchs 

 (Bulloidea), near the point of origin of the Pleurobranchia. The Ascoglossa are 

 not "specialised ^Eolids " (Pelseneer); but the possible origin of the /Eolids from 

 the Ascoglossa (Bergh) remains to be decided. 



Rawitz, B. — The Structure of the Posteiior Salivary Glands in the Cephalopods. 

 Arch. f. mikr. Anat., xxix., pp. 596-611. 



Thiele, J. — Beitriige zur Kenntniss der Mollusken. II. Uberdie Molluskenschale. 

 Zeit. f. wiss. Zool., lv., pp. 220-51, 1 pi. 



Starting with the shell of Chiton the author carefully describes its structure 

 and its relationship to that of the underlying mantle. The shell consists of 

 four layers : Periostracum, Tegmentum, Articulamentum and Hypostracum. 

 The periostracum is produced by the outerside of the mantle edge, the tegmentum 

 arising from its inner side. 



Turning next to Area, he discusses the triple fold in the mantle edge and the 

 part played by it in the formation of the shell, which last consists of two layers : 

 Ostracum and Hypostracum. The tegmentum of Chiton is equivalent to the 

 ostracum, whilst in the Pelecypoda there is no layer corresponding to the 

 articulamentum. 



In Lithodomus dactylus the ostracum consists in great part of pearl as in 



Nucitla. 



The author has investigated the structure of the shell of Patella and finds that 

 in P. ccemlea the outer layer is like that of Area. In Nautilus the deposition of 

 hypostracum is confined to the limits of the muscular impression and the septa, 

 and the author considers that muscles are never attached to any other layer. 



The paper concludes with a review of the more recent literature : it is a pity, 

 however, the author has not looked up the older writers.— B.V 2 . 



VARIATION. 



Cockerel!, T. D. A. — The Soft Parts of Snails. Journ. Inst. Jamaica, 1893, 

 pp. 17S-9. 



Gain, W. A. — Notes on Varieties. Brit. Nat., 1892, p. 254. 



Gredler. — Helix pomatia, L., v. nov. gratiosa. Nachr. Deutsch. Malak. Gesell., 

 1892, pp. 174-5. 



Sykes, E. Ruthven. — On some Monstrosities of Littorina ritdis, Maton. 

 Proc. Dorset N.H. and A. F. Club, 1892, xiii., pp. 191 -8, 1 pi. 



CLASSIFICATION, NOMENCLATURE, NEW GENERA, 

 AND SPECIES. 



Adams, L. E. — The examples of Zonites eellarius in the Montague Coll. at 

 Exeter. Journ. Conch., 1S92, p. 119. 



Aldrich, T. A.— A New Land Shell from Sumatra. Nautilus, vi., p. 90. 

 Cf. also Sifilwiiaria, " Conchologist." II., No. 4, 1S92, p. 90. 



