GASTEROPODES. 291 



The spawn of this animal is produced in the form of tape or ribband, 

 about an inch broad, and above a line thick. The length depends on the 

 dimensions and the age of the parent. One of middle size (for few attain 

 the dimensions as above assigned) produced what must have contained at 

 least 20,000 ova, in the course of ten days, ending with the first week 

 of February. 



The orifice of the oviduct is on the right side. The end of the 

 spawn first produced is affixed to a solid substance, and the remainder is 

 delivered as a broad waving frill, apparently in one continuous web, 

 where in a convenient position. But probably, from some inconvenience, 

 that which is just referred to was discharged in interrupted portions, not 

 above an inch long, and about three lines broad, resembling a thin white 

 silk ribband. Here the ova were pure white, spherical, not the twentieth 

 of a line in diameter, lodged amidst an albuminous mass. More than 

 one is the thickness of the ribband. Under the microscope the ovum 

 consists of a white central speck, within its own peculiar albumen. 

 Plate XLIII. fig. 5. 



Perhaps the spawn sometimes appears a belt or web, in spiral 

 arrangement, such as Plate XLIII. fig. 1. 



But here I must be allowed to express some embarrassment, espe- 

 cially regarding the parentage of certain extraordinary quantities of 

 spawn, sometimes occurring in the course of observation. The Doris, it 

 is true, is a remarkably prolific creature, like some of the other mollus- 

 cous animals ; and it does baffle conjecture to account for the fate of a 

 vast proportion of its young. The contents of a single mass of spawn, 

 certainly the produce of a single parent, seems to exceed computation. 

 Two examples may be quoted. 



A mass occurred in February, which had been deposited on the out- 

 side of the lower valve of an old oyster- shell, to which the upper valve 

 was still united. This consisted of a waving belt or ribband, from seven 

 to nine lines broad, a line thick, and which could not be under two feet 

 in length, if extended. It was affixed by the edge, in such a position as 

 to be erect, and resembled fine white frills. Plate XLIII. fig. 2. 



Herein were contained ova in millions. 



