36 CURRENT LITERATURE. 



whole mid-gut, i.e. , stomach and liver, as well as end-gut (if we can use the term 

 at all as applied to molluscs), arises from the archenteron, which always exhibits 

 a distinct lumen. The mouth proceeds directly from the blastopore, accompanied 

 by an invagination of the ectoderm, which forms the oesophagus ; consequently a 

 complete closure of the blastopore does not take place. The anal opening 

 corresponds to a small pit at the hinder end of the blastoporal groove. Primitive 

 kidney and kidney, apart from their ectodermic excretory ducts, are of mesodermic 

 origin ; the same is true for the heart and pericardium. The ganglia arise com- 

 pletely separate from one another, and do not come into connection until 

 afterward." 



The Cleavage of the Ovum in Crepidula fornicata. (Zool. Anz., 

 p. 185, 1892.) — E. G. Conklin. 



HABITS AND HABITAT. 



The Genus Rissoa. (Brit. Nat., p. 72, 1892.) 



Mr. Brockton Tomlin gives a very interesting account of this genus, giving 

 details as to nomenclature, variation, Sec, which will prove of service to beginners. 



The Limpet's Adhesive Power. (Nat. Sci., p. 319, 1S92.) 



Mr. J. Lawrence-Hamilton, after experiment, finds nothing to suggest any 

 sucker-like action, and concludes that the major part of the adhesive power is due 

 to a secretion of the animal. [In this he agrees with Reaumer, Johnston, and 

 Jeffreys.] 



Observations on two rare British Nudibranchs. (Ann. and Mag. N. H., 

 p. 378, 1892.) 



Mr. F. W. Gamble figures and describes Lomanotus genei, Verany, and 

 Hancockia endactylota, Gosse, both of which have lately occurred at Plymouth. 

 Interesting observations are given relative to the papillae, and a useful table 

 comparing the different specimens of Hancockia and Govia. 



The Genus Cristaria. (Nachr. Deutsch. Malak. Gesell., Jan. and Feb., 1892.) 

 Von Ihering writes on this genus, at present only known from E. Asia, and 

 its relations to the other groups of Unionida. 



Rissoa parva, DaO, v. nigra, Norman. (Brit. Nat., p. 127, 1S92. — 

 B. Tomlin. 



NEW SPECIES. 



Mollusca of Galapagos Islands. (Journ. de Conchl., Oct., 1S91.) 



Ur. Dall mentions the discovery of some interesting molluscan novelties in the 

 Galapagos Is. These are a species of Helicina (nesiotica, Dall), of Leptinaria 

 \chathamcnsis, Dall) and a small ? Zonites {baueri, Dall). All three genera are 

 new to the group. 



New Shells from the Palaearctic Region. (Verhand. d. Zool. Bot. Gesell. 

 in YVien, B. xlii., p. 25.) 

 This is practically a reprint of a paper published by Dr. Westerlund in the 

 Versammlung last winter. Many new species and varieties are described ; 

 principally Helices of the section Xerophila. The one of most interest to British 

 conchologists is H. la?npra from Aran, Co. Galway [This is very near if not 

 identical with H. ericetorum\ Dr. Westerlund also suggests a classification of 

 Sieiliaria — a sub-genus of Claiisilia — in which he groups together CI. crassicostata, 

 CI. leiuophryne, CI. nobilis ; then CI. confinata ; also CI. tiberi, and CI. calcarce ; 

 and finally CI. grohmaniana, and CI. septemplicata. [This latter species is hardly 

 •satisfactory, its lamellae and general facies would incline one rather to place it 

 with CI. coiifinata.] 



