190 DR. T. DAVIDSON ON EECENT BRACHIOPODA. 



Hah. Mediterranean and iEgean Sea, attached to rocks and coral at a depth of from 

 40 to 150 fathoms (Forbes) ; Gulf of Lyons, Banyuls-sur-Mer, in from 50 to 60 metres, 

 on rocks (L. Jouhin). 



Obs. This Mediterranean shell seems to have been described for the first time by Poll 

 in 1795. He gave enlarged illustrations of the interior, to show the position of the 

 principal muscles, mouth, labial appendages, and vascular impressions ; but, strange to 

 say, he described the animal under the name of Criopus, and the shell by that of Criopo- 

 derma. As observed by Dall {loc. cit. p. 36), " Poll evidently considers Anomia as a 

 synonym, and only uses it by way of explanation. It is evident that such a system of 

 nomenclature as the above can never be fairly squared ^vith the binominal system." 



By some malacologists Crania tarhinata has been considered to be the same as 

 or a synonym of Crania anomala, by Dall as a variety of the last-named species, 

 and by some others as a distinct form. I have therefore preferred to leave it, for 

 tlie present at least, as a separate species. It certainly bears considerable resem- 

 blance to the northern form, yet it possesses some peculiarities of its own. It is, on the 

 whole, a smaller shell, differing in colour as well as in some of its interior details. Its 

 upper valve is generally less conical ; but exceptional examples of the Mediterranean 

 shell are quite as conical or limpet-like as some of those that occur in the northern seas. 

 Crania turhinuta is often much out of shape from having its thickened lower valve 

 attached to corals, to which it moulds itself, as in the case of the specimen figured by 

 Sowerby in pi. xxvi. fig. 3 c of the ' Transactions ' of the Linnean Society of London for 

 1818, under tlie name of Crania personata. Sowerby considered that species and 

 C. auomala to be one species ; for he says that " the only difi'erence observable between the 

 specimens from Shetland and those from the Mediterranean is in the thickness and 

 irregularity of the lower valve ; those from the latter sea being very thick and irregular ; 

 wliereas those from Shetland are much thinner and more regular in their shnpe ; but this 

 difference, I imagine, may be easily accounted for from the different situation of the 

 respective specimens ; the one being found upon rugged old corals, and the other being 

 attached to a comparatively smooth stone." (See Plate XXVII. fig. 22.) 



This is no doubt the case with respect to the Mediterranean form. On a specimen of 

 coral now before me three examples of the lower valve are attached, one of these, affixed 

 to a flat portion of the coral, is perfectly regular in shape, the other two being attached 

 to the circular part of the coral are irregular in form, the shell having been obliged to 

 follow the irregularities of surface, which were imparted to the shell itself. 



There appears to be likewise a good deal of difference in the shape and projections or 

 depressions of the mvxscular scars in different specimens, and it is on these differences 

 that Hoeninghaus seems to have established his Crania rinc/ens (Plate XXVIII. figs. 

 1-1 «) and C. rosirata (Plate XXVII. fig. 21), both Mediterranean shells, which I 

 believe to be synonyms of the Crania tnrhinata of Poll. The so-termed C. ros- 

 trata figured by Reeve in his Conch. Icon, does not agree with Iloeniughaus's 

 figures of his species. Thus in the type of C. rin(jens the divaricator scars are 

 figured as large sunken-iu depressions, only slightly separated, and the occlusors as 

 formed of a large transverse oval-shaped scar, no rostellum being present ; while 

 in C. rosirata the divaricators are more separate, and the adductors have a more 



