Fig. 79. Plan of biological raft used at Monomoy Point for growth experi- 

 ments and .spat collecting. The raft, 20 feet long by 10 feet wide, provided with 

 a central well and four trap-doors, was anchored in the Powder Hole in 20 feet of 

 water. Wire cages and wooden boxes were suspended at various depths from the 

 raft. Many kinds of mollusks were caught and raised in these spat boxes. The 

 raft proved particularly useful in the study of the post-embryonic life history, as 

 the scallops "set" in large numbers on the boxes, cages and ropes, where speci- 

 mens could be obtained in all stages of development for laboratory examination. 

 Also, many interesting growth experiments upon the quahaug, scallop and clam 

 were conducted in the sand boxes. 



