14 



Of these the smallest, Cascinodisais perforatiis was by far the 

 most abundant and on all the occasions but one when the water 

 in the pass was examined, this species was found to be more nu- 

 merous than the others. A notable exception to this was one after- 

 noon in September when the surface of the Gulf was almost cov- 

 ered with a pure colony of Eupodiscus radiatus. This form was 

 never seen in such quantities before or after ; neither was one 

 highly nutritious diatom, Melosira punctata, ever found in the 

 stomachs of the oysters after a preliminary examination made in 

 April. These facts show how fluctuating food conditions were.* 



OBSERVATIONS ON THE NEW GROWTH. 



NUMBER OF SPAT CAUGHT. 



In place of the adult oysters exterminated by the freshet a prom- 

 ising new growth has appeared which under favorable conditions 

 will completely restock the old reefs. On July 9th in an exami- 

 nation of reef No. i (see map) near the head of the pass 22 

 young oysters were found on 100 shells. This number is what 

 might have been expected ft-om the location of the bed in the least 

 salt water of the pass. On September 22nd when a second count 

 was made on this reef a great increase in the number of spat was 

 found. At this time there were 156 young oysters attached to 100 

 shells, 109 being on the inner surfaces, and 47 on the outer. Thus 

 almost 70 per cent, of all the spat caught was attached to the inner 

 and cleaner surfaces of the shells. 



On reef No. 2 (see map) one of the first of the two so-called 

 "Sister Reefs," there were on July 9th, 57 young oysters on 100 

 shells and on September 22nd 109, of which yy were on the inner 

 surfaces, and 32 on the outer. Here almost 71 per cent, or about 

 the same proportion as on reef No. i had settled on the cleaner 

 surfaces of the shells. The total number found on September 22nd 

 on reef No. 2 was less than on reef No. i in spite of the fact that 

 the former is further down the pass than the latter. The expla- 

 nation of this may be that such counts as can be made give only an 

 approximate idea of the general conditions of a reef, but the dis- 

 crepancy nevertheless illustrates a point of great importance — the 

 absolute necessity of taking local circumstances into consideration 

 in ovster culture. 



*A table of figures obtained from the examination of water and stomach contents 

 may be found in Appendix B. 



