MOLLUSCA. 



111 Bapa tenuis the nidimeutal capsules are attached 

 in regular linear series to portions of decayed wood ; they 

 are of a flattened subconical figure, adhere by the apex, 

 and have the base emarginate. In Murex endka the 

 cases are tricarinated, one of the keels being bifid. In 

 Tritonium scaler they are flattened and quadrangular, with 

 four keels. In Conus cajntaneus they are curved, with a 

 dorsal keel, and with the free end falciform. In Busycum 

 affine the capsules are arranged in a long string; they 

 are oval, flattened, keeled, the edges angled, and attached 

 by a short peduncle. 



To enumerate a few more examples of the oothecce of 

 marine Gasteropods, — in Acantliina tmicornis they are 

 cylindrical, and adhere by slender peduncles in densely- 

 packed masses. In Chot^us monoceros the somewhat 

 columnar egg-cases are united by slender peduncles in 

 a large rounded mass, the capsules having lids which the 

 young push off. In Valuta they are hard, vesicular, and 

 fixed by broad bases, each containing but one embryo. 

 In Volutella they are large and hemispherical. 



The eggs of the NaticidtB are deposited in flat, spirally- 

 rolled bands, which are partly buried in the sand ; they 

 have been mistaken for zoophytes, under the name of 

 Flustra arenosa. The eggs of Nerites and Neritinas are 

 ovate, covered with a horny shell, and afiixed to the 

 surface of stones or to other shells. The egg-mass of 

 Gihhula cineraria is in the form of a white gelatinous 

 riuQ-, with a narrow break on one side. 



In the Opisthobranchiate Mollusks the oothecce are no 

 less curious. In Aplasia they are excluded in a long- 

 string. In Philine the string is necklace-shaped, and 

 coiled in a loose spiral. In the Tritoniidce, or Sea-slugs, 

 the ova are expelled together in the form of a long thread. 



