IIEPORT ON THE LAMELLIBRANCHIATA. 



GENERAL REMARKS ON THE COLLECTION. 



I have already given a brief notice of the collection, which will be found incorporated 

 in tlie Narrative of the Voyage,^ and the views there expressed require little modification. 



The collection, as a whole, is in some respects disappointing. Considering the 

 character of the Expedition, the appliances with which it was furnished, the able staff of 

 scientific men on board, and the number of Stations dredged, it certainly does seem 

 surprising that only about five hundred species" should have been obtained. This, 

 however, may not be three-fourths of the number of forms which actually passed into 

 the dredge or trawl, for doubtless a certain proportion, perhaps a large percentage, of 

 the secured material, and possibly some of the most valuable, must have found its way 

 through the meshes of the network during the process of hauling in, especially from 

 very great depths. Another disappointing feature of the collection is that the species 

 are represented in tke majority of instances by very few specimens, there being of 

 many of them but single or a few odd valves, some of which arc in a bad state of 

 preservation. The greater part of the collection consists of species from comparatively 

 shallow water, Torres Strait, the Arafura Sea, Port Jackson, Bass Strait, Fiji, Kerguelen 

 and Marion Islands, supplying a large proportion. 



As might be expected, some of the forms are of particular interest when great depths 

 have been reached, but it is a remarkable fact that only one distinctly new generic type 

 was discovered.^ 



The greatest depth at which Lamellibranchs were obtained was 2900 fathoms 

 (Station 244, in Mid North Pacific). Of the two species from this enormous depth 

 one is a small fragUe shell which I have named Callocardia i^acijica; I should here 

 observe, and it is a most interesting fact, that a second species [Callocardia atlantica) 

 was dredged in 1000 fathoms off the Azores, which is all but identical with that 

 from the Pacific. A third species of this genus [Callocardia adamsii) was also obtained 

 in very deep water in the Atlantic to the south-west of Sierra Leone. The second species, 

 from Station 244, belongs to Ahra, which I regard as a subgenus of Semele. 



The other Stations, ranging from depths of 1000 to 2650 fathoms, at which Lamelli- 

 branchs were obtained are Nos. 45, 47, 56, 70, 71, 73, 78, 85, 98, 104, 106, 113, 133, 

 135E, 137, 146, 157, 158, 184, 198, 205, 216, 218, 244, 246, 271, 281, 300, 302, 317, 

 323, 325, and 348. I have quoted these numbers so that reference can be made to the 



1 Narr. Cliall. Exp., vol. i. pp. 624-02B, 1S85. 



2 This does not include a small number of species represented only by odd valves, which are beyond identification 

 owing to their younj; state or bad conditidn. 



' A still more remarkable absence of generic novelties occurred in the case of the Brachiopoda, not a single ntw 

 form having been described by Mr. Davidson. 



