96 The Pearl Oyster of Ceylon, [no. 5, new series, 



which impregnates the ova contained in them and is then dis- 

 charged as an excretion by the oviducts." To this observation of 

 Garner I have to oppose the fact, that not a trace of ova was seen 

 in the ovaria of the supposed male Pearl Oysters, which were dis- 

 tended with the milky fluid at the time when the ovaria of other 

 Oysters were distended with ova. 



The last, though not the least important part of the animal, 

 is the foot. This important member, which has so many useful 

 services to perform in acephalous molluscs, requires a more than 

 ordinary consideration. It is that long, brown, leech-like mem- 

 ber, which is seen when the animal is at rest coiled up in a corner 

 on the light side, above the byssus which, when protruding out of 

 the shell, and moving about, gives one the popular idea of a tongue. 

 It is of a dark brown colour above, and whitish beneath ; in mid- 

 dle age it is speckled. It is composed of longitudinal and trans- 

 verse muscular fibres, the latter interlacing between the former, 

 which proceed in two columnar masses from each side of the ad- 

 ductor muscle ; between the bundles or fibres, are placed the ab- 

 dominal viscera. From its base is sent off, posteriorly, a glisten- 

 ing white fibrous band ; this is attached to the duplicature of the 

 mantle, near the angle of the valves. Thus, the foot is seen to be 

 admirably adapted for locomotive powers ; and also serves, by its 

 connection with the adductor muscles, to lengthen or shorten the 

 cable or byssus. The foot, in a full sized Oyster, is about two 

 and a half inches long when extended ; at rest, it-is not more than 

 one and a half inch in length. It is broad at the base, tapering, 

 to a conical point ; the upper surface is rounded and smooth, the 

 lower flattened and grooved. The groove extending from the base, 

 terminates at the point in an oval cup-like fosset. This groove is 

 lined by a secreting membrane, and is an exact mould for the for- 

 mation of the byssus, at the will of the animal. When it finds a 

 necessity for making one, the foot is protruded out of the shell, and 

 with the tip it seeks out a spot, where it can rest the terminal disc 

 of the groove. If not satisfied with the substance or position of 

 the stone or any other matter on which it rests, it removes to an- 

 other more suitable spot ; for a few minutes (say five or six, if the 

 animal is strong) it rests, and is then retracted within the shell, 



