62 



July, while the shell bears ever}^ mark to indicate that 

 it probably is of one season' s growth, being spawned in 

 the early part of the breeding term. 



It will be noticed that all excex)t Fig. 18 are hand- 

 somely rounded in shape not unlike a scallo]3 in form, 

 which they simulate still more by the lobes which they 

 develop on the shell on either side of the hinge. Bands 

 of a purplish color also radiate from the hinge, widening 

 towards the margin of the valves, giving the spat a very 

 much more handsome ax3pearance than the adult, from 

 which it differs also in having an extremely thin shell 

 which is easily crushed or broken. The rounded forms 

 were taken from the liat surfaces of the slate collectors, 

 though Fig. 18, the only one noticed which exhibited a 

 tendency to elongate like the adult, was taken from a 

 similar surface. If the fry happens to fix itself to a 

 roughened surface or in an angle it will adapt itself to 

 the shape of the nidus which it has chosen. In one case 

 I found a small oyster about a fourth of an inch in diam- 

 eter attached to the outside of the plicated shell of a 

 Modiolaria, and was surprised to notice that in growing 

 and adapting itself to the wrinkled surface of its host it 

 had reproduced in both valves all the folds on the out- 

 side of the former. I also found a specimen which had 

 fixed itself to a dead sponge. 



js^umbek of spat which fix themselves to a single 



SLATE. 



As I have remarked above the most successful collect- 

 ing apparatus was found to be the slates covered with a 

 coating of mortar, but even these did not give the most 

 promising results, as the greatest number of spat noticed 

 on one slate was 8, varying from i to 1 inch in diameter. 

 This meagerness in the number of young which fixed 

 themselves last summer may have been due to an unfav- 

 orable season. The results obtained by Captain Wins- 

 low as detailed in the report of this Commission for the 



