ORBICULA. 7 



3. Orbicula lamellosa? Brod. Plate I, fig. 9, 9 aJ . 



Orbicula lamellosa, Brod. Zool. Proc, 1833, p. 124. 

 Discina norvegica? S. Wood. Mag. Nat. Hist., 1840. 

 Orbicula norvegica, Tennant, A Stratigraphical List of British Fossils, p. 17, 1847. 



Diagnosis. Shell inequivalved, nearly orbicular, longer than wide ; upper valve of a 

 flattened conical form, much depressed, vertex acute, prominent, situated at a third of the 

 length of the valve from the posterior margin j surface ornamented only by minute 

 concentric lamella or lines of growth; colour a ferruginous yellow. Structure horny. 

 Length 2, width 1| lines. 



Obs. The discovery of this small orbicula is due to Mr. S. Wood, who found it in the 

 Coralline Crag of Sutton. Unfortunately only one imperfect specimen of the upper valve 

 has been procured, so that its determination is difficult and uncertain. We have referred it 

 for the present to the recent Orbicula lamellosa, which it resembles, until a perfect specimen 

 comes to light, on which a more accurate determination may be arrived at; it has also some- 

 thing of the appearance of 0. lavis. Mr. S. Wood, in his 'Catalogue of Crag Mollusca,' 

 attributes it to the Discina norvegica, which seems a mistake, that species being Crania 

 (Patella) anomala of Miiller. 0. lamellosa is at present found recent in various parts of the 

 coast of Peru; and is, as well as all the species of the genus, an inhabitant of tropical lati- 

 tudes; and we may here state, also, that it is found in company with a Lingula L. Dumontieri, 

 a genus likewise peculiar to much warmer seas than those which wash our shores. 



Fig. 9. A specimen, natural size, from the Collection of Mr. S. Wood. 



Fig. 9 a b . Enlarged representations. 1 



1 It has been thought advisable to introduce a reference to the only recent Cranium, C. anomala, that 

 occurs in the British Seas, in order to render the sequence of genera referred to in the table complete. 



Otho Frederic Miiller appears to have been the first to bring this species into notice, styling it "Vermis 

 singularissimus," and placing it as an anomalous form of Patella : it has been well described by Professor 

 Forbes, in his work on ' British Mollusca.' He states : " The arms are extended horizontally, each forming 

 a rather short, graceful, plume-like curve ; the fringes are long, rather stiff, and can be extended slightly 

 beyond the shell ; they are of a fleshy white colour ; when the upper valve is removed, the fringed arms are 

 seen lodged in it ; the ramifying ovaries, which are of a tawny hue, remain on the under valve." 



This species has hitherto been only found in the recent state ; and it appears common near some of 

 our shores, especially on the West Coast of Scotland. It was first found adhering to stones in deep water in 

 Zetland by Dr. Fleming. Professor Forbes adds many interesting details relative to the localities and depth 

 of water in which it has been collected. Thus, he adds, it is found "off Arran in twenty fathoms (Smith) ; 

 Loch Fyne in thirty to eighty fathoms ; plentiful on stones off Mull in twenty and ninety fathoms ; off 

 Lismore in from twenty to thirty fathoms ; off Armadale in eighteen fathoms ; off Copenhaw Head, Skye, in 

 forty fathoms; on the Ling Banks off Zetland in fifty fathoms (M 'Andrew and E. F.) ; Loch Alsh, Loch 

 Carron, Ullapool, East of Lerwick, in forty fathoms (Jeffreys). In Ireland it has been taken off Youghal 

 by R. Ball, and off Cork by Humphreys. It ranges throughout the Scandinavian seas." 



Plate I, fig. 1. Specimens, natural size. 



„ fig. I". Interior of attached valve, considerably enlarged. 

 ,, fig. 4 . Interior of upper valve, enlarged. 



b 



