272 EVExrxGS at the mickoscope. 



Bj comparison of this organ witli tlie corresj^onding 

 parts in other genera, there is every reason to infer that 

 this tnrhid mass is an enormous brain, the nervons 

 matter Lehig in a very diffuse condition ; and that the 

 ruby seated on it is an eye, consisting of a crystalline 

 lens, and a layer of crimson pigment beneath it. 



The oval bodies that you see attached to the hinder 

 part of the shell are eggs. Most of the females that 

 we meet with caiTV one or more, sometimes to the num- 

 ber of six or seven. The specimen we are examining 

 had two at first, one on each side the foot-orifice ; but 

 just now a third was excluded — an operation which 

 occupied but an instant — and this took its place be- 

 sides the former two, so that we now see three. These 

 eggs are generally carried by the parent until the 

 young are hatched. The oldest of these three is nearly 

 ready for hatching, and if you watch awhile you will 

 see the birth of the young. At first exclusion, the eg^ 

 which was seen some time before in the ovarv, as a 

 semi-opaque mass, of well-defined but irregular shape, 

 immediately assumes a form perfectly elliptical, and its 

 coat hardens into a brittle shell. This is so transparent 

 that the whole process of maturation can be watched 

 within the shell. Tlie yelk is at first a turbid mass, in 

 M'hich are manv minute oil-globules. Soon it divides 

 into two masses, then into four, then into eight, sixteen, 

 and so on, by the successive cleavage of each division, 

 as fast is it is made, till these divisions are very nu- 

 merous. Then we begin to see spontaneous move- 

 ments ; the outline of the young separates in parts 

 from the wall of its prison, folds are seen here and 

 there, and fitful contractions and turnings take place. 

 Soon an undefined spot of red appears, which gradually 



