Miscellaneous. 353 



form of the bill and feet are similar to those of the genus proposed 

 above. 



The specimen of Caulodromus was kindly lent me by J. R. Grace, 

 Esq., who procured it in Darjeeling : that of Salpornis was presented 

 by B. H. Hodgson, Esq. to the British Museum, and forms part of a 

 collection from Behar. 



MISCELLANEOUS. 



Microscopic Anatomy of the Shell of the Decapodous Crustacea, 

 By J. Lavalle. 



From my observations, says the author, the tegumentary apparatus 

 of the Crustacea may be divided into two parts : 1st, an exterior one, 

 which is incrusted with calcareous salts, and has no apparent ves- 

 sels ; it is the carapace, the shell properly so called ; it alone forms 

 the solid skeleton of the animal, and its inextensibility requires it 

 to be shed at certain periods, to be replaced by a larger covering. 

 2nd, the other, situated in the interior, covers the first at all points : 

 it is soft and highly vascular, it remains after the shedding of the 

 tegument, and appears to be especially destined to reproduce a 

 new one. 



My observations apply to the shell alone, to that portion of the 

 tegumentary apparatus which is cast annually, and I have purposely 

 limited the subject, because it has been hitherto almost impossible to 

 base a sufficiently, settled opinion upon the nature of this coriaceous 

 and hardened covering. 



The solid portion of the tegumentary apparatus of the decapodous 

 Crustacea which is shed differs essentially from shells, in one thing, 

 that when treated with an acid it parts with its carbonate of lime 

 without its organization being any way changed. In this respect it 

 may be compared to the bones of the vertebrate animals. 



The shell constitutes a covering of a single piece, continuous 

 throughout, and which is only interrupted on the level of the natural 

 openings. The flexible points, and the softest parts of this envelope 

 diff*er from the solid parts only in the absence of calcareous salts ; 

 their organization is perfectly identical. The articulations are only 

 more or less complicated, but often very simple folds, of this cover- 

 ing. It is the same with the ossiform parts placed withinside the 

 organs, and designed for the insertion of the locomotor muscles. 

 The parts destined to break or grind the food are only more solid 

 parts of the shell and of a denser texture. At the time of shedding, 

 all these parts are cast oif together. The shell presents, in the most 

 perfect state, three layers quite distinct and easily separable : — "ITie 

 most external, homogeneous, transparent and corneous one, presents 

 an opening only for the passage of the hairs or analogous organs, 

 and covers the whole shell with a varnish often extremely thin ; it 

 is evidently analogous to the epidermis of the higher animals ; I have 

 designated it by the name of epidermal layer. The central layer is 

 Ann. ^ Mag. N. Hist. Vol.yiw. 25 



