310 GASTEROPODES. 



specimens remained, the one smaller and weaker than the other. The 

 union of this pair seemed to have taken place, and to have been produc- 

 tive. Yet soon afterwards, the larger unexpectedly devoured its mate, 

 all except a portion, then conjectured to belong to the head, from which 

 it endeavoured during hours to extract further nutriment. 



A third specimen, previously in the same vessel, likewise smaller 

 and weaker, had disappeared, having been probably devoured by its com- 

 panions. 



The older observers considered the Doris a hermaphrodite animal. 

 But this opinion may be safely abandoned, by admitting the usual course 

 of nature. The preceding union was on the 4th of October : spawning 

 followed next morning, though probably not its consequence. 



If the parent be vigorous, the spawn is deposited as the most regu- 

 lar undulating logarithmic curve of several volutes. But it appears in 

 small spiral masses if the parent be attenuated. 



The transparence of the body exposed the formation of the ovarium 

 in clusters, as if occupying the whole cavity of the abdomen, towards the 

 close of August. Yet the first spawning did not precede the 5th of 

 October. The third on the Sth of October, consisting of seven entire and 

 uninterrupted volutes ; and another of five, followed on the llth. This 

 was succeeded on the 10th by four volutes, more perfect and regular, if 

 possible, than any of the former, fig. 6. Now it was computed that the 

 whole hitherto produced might have extended twelve inches in one un- 

 interrupted line. Spawn appeared at four subsequent intervals until 

 November 6. 



The orifice of the oviduct opens under the first branchial cluster on 

 the right side. From hence the spawn issues like a coarse white thread. 

 of albuminous consistence, studded throughout the diameter with ova. 

 The extremity of the line first discharged being affixed, the parent re- 

 cedes slowly and gradually in circumferential progression as expulsion 

 of the thread continues, until the whole spiral figure is completed. But 

 this is a very slow process, an hour being consumed in producing two 

 volutions. 



Here the diameter of the figure of the earlier spawn was six lines. 



