On the Mascarcve \'lverrid GaVidicl'is. 113 



structure of these bones. The structure of the griiiding- 

 pl-\tes has been described by Schauinshind, who remarks : — 

 " Tlie first deposition of hard material begins at tlie outer 

 surface of the papilla, and takes the form of a thin cap of 

 dentine; soon, however, tiie tooth-substance appears below 

 at the points where the plate is to come in contact with the 

 cartilage of the head ; and almost at the same time trabeculge 

 and lamellae appear between (^'. e., in the substance of the 

 plate), and produce a meshwork of spongy tooth-substance 

 (pulp-dentine). The mode of origin of the plate resembles 

 closely that of bone when derived from connective tissue 

 {e.g., in Sphenodon). The mesenchyme-cells in the papilla 

 are collected together closely at certain points, and become 

 transformed into odontoblasts, and from these, peripherally, 

 the dentine takes its origin. Occasionally trabecules of the 

 dental mass, especially in older individuals, show a somewhat 

 lamellar structure, and those which are tirst differentiated — 

 that is, those lying innermost — are distinguishable from the 

 latter lamellai by their capacity to become stained." 



In Chimara these two abnormal bones are, histologically, 

 quite distinct from the ordinary osseous tissue o£ fishes. The 

 nearest condition I have seen to what obtains here is in the 

 development of certain bones in postlarval Pleuronectids * ; 

 and whilst I am not suggesting that these abnormal bones 

 show the structure of the grinding-plates, as described by 

 Schaunisland (op: cit.), they certainly present some features 

 in common, 'ilie material at my disposal was not in a fit 

 condition for any minute histological examination, but tlie 

 series of closely massed stiands, forming a meshwork of 

 spongy material, strengthens the homology I have suggested. 



I liave pleasure in thanking Professor W. (J. MTntosh, 

 F.R.S., for the wealth of niaterial he has so generously 

 placed at my disposal. 



XVIII. — On the Species of the Mascarene Fi'yerr^V/ Galidictis, 

 loith the Description of a ntio Genus and a JSote on 

 "Galidia elegans." By R. I. POCOCK, F.R.S., Super- 

 intendent of the Zoological Society's Gardens. 



[Plate VJI.J 



Up to the present time only two species of this genus have 

 been admitted, namely, the broad-banded form commonly 



* I have to thank iJr. H. M, Kyle for drawing my attention to this 

 fact, after he had examined the first above-mentioned' abnormalitv. 



