772 SUMMARY OF CURRENT RESEARCHES RELATING TO 
Land Mollusca of the Philippine Islands.* — The Rev. A. H. 
Cooke examines the problem of the ancient relationship of the different 
islands of the Philippine group to one another by the aid of the almost 
peculiar genus Cochlostyla , which is exceedingly rich in species ; he 
also discusses the relations of the Philippines to the neighbouring 
islands. 
8. Ramellibranchiata. 
Classification of Lamellibranchs.|— Prof. C. Grobben proposes the 
following classification of Lamellibranchs. 
Sub-class I. Protobranchiata ; With double comb-like gill, no teeth to 
shell, or interdigitating denticles or taxodont — Ylastidse, Cardio- 
lidae, Antipleuridae, Lunulicardiidae, Praecardiidae, Silurinidae, Proto- 
myidae, Solenopsidae, Grammysiidae, Posidonomyidae, Dionellidae, 
and Nuculidae. 
Sub-class II. Desmodonta: With double-leaf-like gills ; teeth absent or 
irregular — Pholadomyidae, Myidae, Anatinidae, Panopasidae, Sep- 
tibranchia, M.actridae, Pholadidae, and Gastrochaenidae. 
Sub-class III. Ambonodonta : With double-leaf-like gills; teeth mar- 
ginal indentations of the shell, alternate; may be wanting. 
1st Order, Eutaxodonta ; Arcidae. 
2nd „ Heterodonta : Astartidae, Crassatellidae, Charonidae, 
Lucinidae, Cardiidae, Tridacnidae, 
CyrenidaB, Cyprinidas, VeneridaB, 
Solenidas, Tillinidae, and Donacidae. 
3rd „ Schizodonta ; Trigonidas, Najades. 
4th „ Anisomyaria : Aviculidae, Mytilidas, PinnidaB, 
Pectinidas, Spondylidas, Ostreidae, and 
Anomiidas. 
Some comparisons between this system and those recently proposed 
by Neumayr and B. Sharp are made. 
The Mantle-margin of Acephala.J — Dr. B. Rawitz continues his 
study of the mantle-margin, describing that of Lucinacea ( Cardita , 
Astarte , Lucina ) ; Dreissenia polymorpha ; Yeneracea ( Cardium , Cyprina , 
Artemis , Cytherea, Venus , Tapes , Petricola) ; Tellinacea ( Donax , Psam - 
mobia, Tellina ) ; Myacea ( Solecurtus , Solen, Lyonsia , Madra , My a) ; 
Pholadacea ( Teredo and Pliolas'). Of the multitudinous histological 
details which he describes we shall not attempt to give a summary. A 
special chapter is devoted to the epicuticula, which is thin, structure- 
less and transparent in Arcacea and Ostreacea, but shows in other 
orders an increasing thickness, opacity, and complexity. In Area and 
Pecien it is only a very small portion of the marginal epithelium which 
forms the epicuticula, in Mytilacea a larger region is imjfLicated, and 
in the Siphoniata much more; in the last-named forms the layer is 
complex and two-layered. In some Myacea not only the folds of the 
mantle-margin, but the epithelium of the whole external surface of the 
siphon form an epicuticula, which is formed precisely in the way 
that Huxley described in the case of the chitinous covering of the 
crayfish. 
* Proc. Zool. Soc., 1892, pp. 447-69. t Zool. Anzeig., xv. (1892) pp. 371-5. 
\ Jenaische Zeitschr. f. Naturwiss., xxvii. (1892) pp. 1-232 (7 pis., 5 figs,). 
