GASTEROPODES. 323 



free. Another ovoidal mass afforded Nautilines, such as fig. 5, and the 

 empty shells, fig. 6, the parent also being unknown. 



In general, only a single Nautiline is confined in a single ovum or 

 capsule ; but there are examples, as we have seen, of three, four, or five 

 being together. The integument is often of that extreme tenuity as to 

 be almost invisible, and then the common liberty of the inmates is dis- 

 covered chiefly by their interchange of places within their prison. While 

 doing so within this limited space, a barrier environing the whole evi- 

 dently prevents their escape. Perhaps we are yet unprepared for dis- 

 cussing this question, which must necessarily remain in much ambiguity 

 amidst such scanty materials. Very little of the spawn of aquatic animals 

 is known to naturalists, who can determine but little as the pristine pro- 

 duce of different tribes. 



Pendulous clusters, of which we do not witness the origin, are fre- 

 quently found on the Corallines, the Scrtularia falcata or lialecina, for 

 example, composed of spherules under half a line in diameter. They 

 resemble bunches of minute currants, each of which is attached by its 

 peculiar pedicle to a certain part. A cluster of this kind is represented 

 Plate XLVI. fig. 7. A coating of the finest sand sometimes invests the 

 bunches, from which others are entirely free. The sand can be discovered 

 only by the microscope. I have not seen any species of the Doris to 

 which these clusters might be ascribed. 



The clusters, it will be observed, are composed of spherical capsules, 

 either invested by sand, or partially or entirely free of it. On June 11, 

 two capsules, partially free, being subjected to the microscope, exposed 

 a number of irregular quiescent corpuscula, reddish in the one, and 

 yellow in the other. Each of other two contained at least twenty- five 

 corpuscula, also quiescent. Although the skin of the capsules was toler- 

 ably free of sand, their form was too obscure to be distinctly defined. 

 Three of these four capsules are represented as enlarged, figs. 8, 9, 10. 

 But in other two, entirely divested of the sandy coating, not fewer 

 than twenty were discovered pursuing an active course amidst the liquid 

 contents, and the last among them especially interchanging their places 

 everywhere with the rest, figs. 11, 12. 



