LAMELLIBRANCHIATA. 



35 



Remarks on '•Pcctoi fragilis Jeffreys" '). 



As I find nnself able to clear up the obscurity which has hitherto rested over this species of 

 Jeffreys, I take this opportunity of making; a few remarks in this regard. 



Picftu fragilis was founded by Jeffreys in 1876 (Ann. Mag. Nat. Hist. (4) 18, p. 424) for a 

 species taken by the "Valorous" Expedition in the North Atlantic, between Ireland and South Green- 

 land, at depths of 1450, 1750 and 1785 fm. At the same time Jeffreys reports, that the Norweg. 

 North-Atlantic Exped. had taken the same species during its cruise of 1876, at 1000 — 1500 fm.; this 

 latter information must have come through H. Friele (of Bergen), to whom the working up 

 of the Mollusca of the Norwegian Expedition was entrusted, sending Jeffreys a specimen of 

 this Pecten of the northern ocean, which the latter has identified as belonging to his North Atlantic 

 species. 



In 1879 Jeffreys again mentions Pcctcn fragilis, in the report on the Mollusca collected by 

 the "Lightning" and "Porcupine" Expeditions (Proc. Zool. Soc. Lond. 1879, p. 561), a specimen having 

 been taken by the "Porcupine" in 1869 off the west coast of Ireland in 420 fm. On this occasion two 

 figures of the shell are given (1. c. PI. 45, fig. i). 



In the same year Friele stated, that P. fragilis Jeffreys was common over the whole of the 

 deep "cold area" from the Fseroe-Shetland Channel to Spitzbergen. 



On comparing the "fragile" Pecten found by the "Ingolf Expedition in great depths in the 

 "cold area" with the P. fragilis Jeffr. figured in the Proc. Zool. Soc. 1879, PI. 45, fig. i to the right, it was 

 evident to rae, that it must be the same species, and that fig. i to fhr left ou the same Plate must 

 have arisen from the artist turning the right valve round and publishing it as left valve, as it has 

 the auricular sinus (for the byssus) and is on the whole a copy of the right valve. 



I had some doubts, however, as to how far the figure to the right had really been drawn 

 from one of the original specimens of the "Valorous" Expedition, as it is stated regarding these in 

 Jeffreys' paper of 1876: "Fragments only"; nor could I believe, that the specimen of the "Porcupine" 

 Exjjedition had served as basis for the figure, as it is designated "young", whilst the figure in question 

 represents a fairly large specimen. To still further increase the confusion, it is stated in Jeffreys' 

 diagnosis of 1876: "the lower valve has a few slight concentric ribs, but no longitudinal striae", which 

 does not agree with my specimens from the depths of the Norwegian Sea (nor with Jeffreys' figure) 

 and "ears equal in size", which does not agree either. 



I had my suspicions, therefore, that the figure in the Proceedings of the Zool. Soc. had been 

 drawn from a specimen from the deep arctic basin, sent to Jeffreys by Friele. I therefore asked 

 Dr. A. C. Johansen, who was at that time studying at the British Museum in London, to examine 

 into this matter, and through the friendly assistance of Mr. E.A.Smith, the Director of the Malacol- 

 ogical Department, Dr. Johansen was able to send me the following information. 



F'rom the "Valorous" Expedition there were only rather poor fragments of "Pecten fragilis 



I) These remarks are a translation from my earlier article, written in Danish, on Pecten frigidus (1. c). 



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