Fig. 65. External view of the two valves of the scallop. Left valve: A, 

 anterior border; P, posterior border; D, dorsal border; V, ventral border (free 

 edge) ; HH, hinge line; AP, width; DV 7 , height. Right valve: U, umbo; B, byssal 

 notch; E, ears; R, ridge; F, furrow. 



Fig. 66. Shows the method of recording the growth of individual specimens 

 and of obtaining data upon the migratory habits of the scallop. A small hole was 

 bored through the "ear" close to the hinge line with an awl. A numbered copper 

 tag was attached by a fine wire. 



Fig. 67. Generative gland: ov, ovary; t, testis; ep, ciliated epithelium on 

 surface of visceral mass; glc, gland cells; bm, basement membrane; ct, tissue of 

 irregular cells beneath epithelium; fep, follicular epithelium; d, ciliated ducts, the 

 one in the testis containing spermatozoa, and on its walls a gland cell being shown; 

 bv, blood vessel. (This illustration is a copy of a drawing by James L. Kellogg, 

 produced as Fig. 71, Plate LXXXIX., Bulletin, United States Fisheries Commis- 

 sion, 1890, and is published with the consent of Dr. Kellogg. Unfortunately, in 

 the reduction much of the fine detail of the original has been lost.) 



Fig. 68. The oyster drill (Urosalpinx cinerea). An enemy of the scallop, which 

 bores a fine hole through the shell and feasts upon the soft parts. Cases contain- 

 ing the eggs of this mollusk are shown on the right. Life size. 



Fig. 69. Scallop Food. Typical diatoms found in Massachusetts waters, 

 (a, b, c) Navicula, (d, e) Pleurosigma, (f) Nitzschia, (g) Melosira, (h) Chcetoceras, 

 (i) Cyclotella, (j) Licmophora. Magnified 200 diameters. 



Fig. 70. A starfish opening a scallop by slowly dragging the valves apart by 

 means of small, sucker-like feet on the lower side of each of the five rays or "arms." 

 When the valves are forced apart the starfish rolls out its stomach, which envelops 

 the soft body of the scallop. Digestive juices are poured forth and the food is 

 digested outside the body of the starfish. This creature is the most destructive 

 natural enemy of the scallop, and in certain localities has made serious inroads. 

 It is best killed by steaming or bringing ashore. 



Fig. 71. Diagram of the wire cages in which scallops were suspended from 

 the raft at Monomoy Point. The cage consists of a framework of wood covered 

 with 1^-inch mesh wire netting. 



Fig. 72. Plankton net, made of silk bolting cloth, used to catch the swim- 

 ming shellfish larvae. The net is towed through the water behind a rowboat. 



