107 



Armstrong, Lee R. 1965. 



Burrowing limitations in Pelecypoda. Veliger 7(3): 195-200. 



Experiments were made on 10 clam species (Mereenaria not included J to 

 determine how clams, once in position and covered with sand, could elevate 

 themselves back toward the surface. It was demonstrated that clams do not 

 elevate voluntarily in their burrows. Directional movements were rota- 

 tional and downward only. All species studied, including Protothaea 

 staminea and Saxidomus nuttalli , which are similar in external morphology 

 to Mereenaria , were less dense than the medium in which they live, so that, 

 when agitated, they were buoyed upward. Clams subject to wave action can 

 regain normal posture as long as they are not buried with siphons down. 

 (Abstracter's note: It would be interesting to repeat these experiments 

 with Mereenaria mereenaria .) - J.L.M. 



108 



Arnold, Augusta Foote. 1901. 



The Sea-Beach at Ebb-Tide. Dover Pubs. Inc., New York (reprinted 1968), 

 xii+490 p. 



Hard clam ranges from Cape Cod to Florida in shallow, muddy bays and 

 estuaries or sandy open deeper bays or open ocean. Harvest is extensive 

 from Cape Cod to Cape May with rakes. Greatest length is about 3" and 

 height 2 1/2". The species increases in size and bulk toward the south, 

 sometimes reaching 5 lbs and 6" diameter. The shell is distinguished by 

 prominent umbones directed forward, heart-shaped lunule, external ligament, 

 concentric sculpturing of growth lines, pure white interior sometimes with 

 violet zones around muscle scars and margin, three stout cardinal teeth, 

 fine crenulation inside ventral margin, and sharp-angled pallial sinus. 

 - J.L.M. 



109 



Askew, C. G. 19 72. 



The growth of oysters Ostrea edulis and Crassostrea gigas in Emsworth Harbour. 

 Aquaculture 1: 237-259. 



Hard clams held in separate trays at each site became smothered with silt and 

 suffered almost total mortality. Thus no results on Mereenaria mereenaria 

 were included. - J.L.M. 



11C 



Atkins, Daphne. 19 36. 



On the ciliary mechanisms and interrelationships of lamellibranchs . I. 

 Some new observations on sorting mechanisms. Quart. J. Micr. Sci. 79(314): 

 181-308. 



The lamellibranchs studied, in which Venus or Mereenaria were not included, 

 agree in having a sorting mechanism on the gills, composed of adjoining 

 tracts of frontal cilia beating in opposite directions on the same gill 

 filament or leaflet. The arrangement was somewhat different in different 

 groups. Tracts of fine frontal cilia, beating continuously, convey 

 particles intended for consumption, while tracts of coarse cilia, fully 

 active only when stimulated, transport material intended to be rejected. 

 Although these tracts function to sort food, their chief value may be to 

 remove from gills mud or sand which appears in the water periodically. 

 When coarse cilia of rejection tracts are fully active, i.e., when much 

 material is dropped on the gill, they sweep everything in the direction 

 in which they are beating, especially if the particles have become con- 

 nected by mucus, overcoming by their greater strength the action of the 

 fine cilia of the food tracts. The paper is clearly illustrated with 

 many drawings. - J.L.M. 



32 



