LAMELLIBRANCHIATA. 



I'5 



74°35' N. L., iS^is' W. L 79fni., iiuid and stones. 2 sijec. 



Off Mackenzie Bay 58 - , imul. 10 — 



and the Belgica Expedition at tlie following places'): 



75° 58-5' N. L., i4°o8' W. L 158 fni., bottom-temp. 0.4° C. 4 spec. 



77°35-5' - - i8°i2' - - 28 - , - - - 1.79° - 16 - 



Thus, at East Greenland llie t\pical ^i. crciiafa has been taken at 13 localities from 70^36' N. E. 

 — 77°35'-5 N. L., and at depths of 50 — 160 fm. The largest specimens are 28""". 



From West Greenland I have only seen it from the above-mentioned St. 29 of the "Ingolf 

 and from Umanak, 250 fm., but I imagine that quite a number of the .specimens, which Posselt records 

 in Consp. Faun. Groenl. simply as '■'•Astartr crciiafa", belong to the typical form. The specimens to 

 hand from Umanak are remarkably short and on the whole much convex, as will be seen from the 

 measurements below: 



Height Breadth 



LeuEtth Height ^ — Breadth - 



*■ " Length Length 



21.5"'"-. 16.3™"'. 75-8% . ii.6""». 54 % 



18.75 - 15-5 - 82.7 - 10.2 - 54.4 - 



18 - 14.2 - 78.9 - 10.2 - 56.9 - 



17.5 - 14 - 80 - 9 - 51.4 - 



17 - 14 - 82.4 - 10.2 - 60 



Var. subcequilatera Sowerby. 

 PI. IV, figs. 5 d and e. 

 Astartc stda-qiulatcra Sowerby, Thes. Conclul. II, 1855, p. 780, PI. 167, fig. 13; Reeve, Conchol. Icon. 

 XIX, 1874, sp. 5, PL I, fig. 5. 



This resembles the typical crcuatn in the oval form of the shell, but the concentric ribs are 

 fewer in number and coarser; the periostracum on the wliole darker, \ellowish-brown, oHve-coloured 

 or brown. 



The form is besides subject to great variation, as will appear clearly from the measurements 

 below; it varies from the elongated-oval or elliptical to the orbicular, somewhat triangular: 



Height , , Breadth 



Locality Length Height ^^^- Breadth ^-^-- 



Ingolf St. 27 27 """. 21.5 "■"". 79-6 % 13-5 '""'• 5° % 



- - 26.5 - 19-5 - 73-6 - "-5 - 434 - 



— - 32 24.5 - 18.25 - 74-5 - IO-75 - 43-9 - 



Julianehaab 24.5 - 21.5 - 87.8 - i4-3 - 584 - 



Jan Mayen 3° - 22 - 73-3 " H " 46-7 - 



_ _ 27.75 - 21.75 - 784 - 14-5 - 52-3 - 



■) Grieg, in Due d'Orleans: Croisiere occanographique, 1909, 13.534. 



15* 



