484 DR WHEELTON HIND ON 



1893. Ulrich, Geological Survey of Ohio, vol. vii. In the volume the following new genera are described, with 

 many species : — B y stony cl da, Anomalodonta, Miller ; Eridonychia, Allonychia, Opisthoptera, Meek ; 

 Psilonyrlda, Anoptera, Clionyclria, Modiolodon, Actinomya, Colpomya, Cymatonota, Psiloconcha, 

 Ortonella, Ischyrodonta, Wliitella, Pyrenomoeus, Hall ; Technoplwrus, Miller ; Cydoconcha, Miller ; 

 Rhytimya, Physetomya. 



The dates of those genera must be carefully examined, for the volume quoted above often refers 

 to the Final Report, vol. iii., Geological and Natural History Survey of Minnesota, which is 

 referred to as 1893; but the completed volume itself only bears the date 1897. In the Ohio 

 volume Ulrich speaks of the Minnesota paper as being in the press. 



1897. To the volume on Minnesota just mentioned Ulrich contributed "The Lower Silurian Lamelli- 

 branchiata of Minnesota." The generic description of Modiolodon and Byssonychia and others, for 

 example, referred to in vol. vii. of the Ohio report, dated 1893, only appears in the Minnesota 

 volume dated 1897, but on the title-page the date 1892-96 is printed. The following generic 

 descriptions also occur in the latter volume: — Clionychia, Eurymya, Actinomya, Aristerella, Endo- 

 desma, Plethocardia, Saffordia. 



1900. Handbook on the Natural History of Glasgow and the West of Scotland, Brit. Assoc. A description 

 of the Silurian rocks in the South of Scotland is given by Messrs Peach, Hornb, and Macconochie, 

 with a description and table of strata, and a list of fossils. 



1902. Cowper Reed, Geol. Mag., dec. 4, vol. ix., describes and figures Salter's undescribed species, among 

 which are the following lamellibranchs : — Pterinea exasperata, P. condor, Goniopliora grandis, 

 Modiolopsis minus, Orthonota Hughesi. 



1905. Cowper Reed, Geol. Mag., dec. 5, vol. ii. p. 492, gives a list of seventeen species of lamellibranchs 

 from the Redhill and Slade beds of Haverford West, nine of which are new. 



Protopecten, genus nov. 



Generic Characters. — Shell erect, ovate, moderately convex. Antero-superior and 

 postero-superior angles compressed and slightly subalate. Hinge plate straight, 

 flattened, edentulous. Umbones subcentral, small, very slightly elevated. Pallial line 

 entire. Surface ornamented with retiform or crenulate markings. 



Observations. — There are two shells in the Gray Collection which seem to me to 

 show a tendency to a Pecten-like form, especially in the ornament ; one, Protopecten 

 vimineus, has a very delicate basket-like appearance ; the other, P crenulatus, shows 

 distinct crenulate lines of growth in its older stages. The ear-like condition of the 

 anterior and posterior superior angles and the generic shape and ornament suggest an 

 approach to the Pectinidse, a family very poorly represented in the older rocks. 

 Unfortunately, the material on which I have- erected this genus is small and the 

 specimens not quite complete, but I know of no other genus in which to place them. 



Protopecten vimineus, sp. nov. (PI. I., figs. 2, 3.) 



Specific Characters. — Shell small, almost equilateral, erect, narrow transversally, 

 ovate, regularly moderately gibbose. The margin is formed by a continuous curve, 

 which is broad in front and behind and more acute below. The hinge line is straight, 

 nearly equal to the transversal diameter of the valve. The umbo is small, tumid, very 

 slightly elevated, central. 



