OF MASSACHUSETTS. 47 



(1) The Mouth and (Esophagus. - -The primitive m<uith ;m<l ci-soph- 

 a.-us in the Nelker consisted of a simple ciliated funnel leading into the 

 stomach. Al this period the edges of the mouth were covered with cilia, 

 and the palps had not made their appearance, the only fundamental 

 difference between the mouth of the veliger and of the adult. 



(c) The 5/owr7/.--Tlie stomach of the veliger can be discerned 

 ath the liver through the transparent shell. The walls are lined 



with cilia. The adult stomach is more specialized by the formation at 

 the posterior end of the articulating receptacle for the head of the 

 crystalline style, by its larger size, and the ridges and folds which line 

 its inner surface. Its development is gradual with the rest of the soft 

 pails of the scallop, but cannot be traced in the young scallop after the 

 veliger stage, owing to the dark covering of the liver. 



(d) The Liver. - - The liver appears in the veliger stage as two glands 

 on each side of the stomach, and rapidly spreads out to cover that 

 organ, so that in the developed veliger the most conspicuous object is the 

 lame liver mass in the center of the animal, with its granular colored 

 appearance. As the scallop grows older, the liver takes on a darker 

 color, which in the adult is an extremely dark brown, whereas in the 

 young scallop, even up to 15 millimeters, it is a light brown or occa- 

 sionally a j'ellow brown. 



(e) The Intestine. The intestine of the veliger when first formed 

 is a simple tube curving downward and backward from the stomach. 

 In a few hours the digestive processes have necessitated greater use of 

 this organ and it has accordingly elongated by forming a coil in the 

 upper part of the mantle chamber above the stomach and liver. The 

 entire length of the tube is lined with cilia, and the food particles can 

 be seen rotating within. The successive development of the intestine, 

 exclusive of the formation of the crystalline style, which lies in a folded 

 groove in the portion near the stomach, is chiefly that of elongation by 

 means of coiling. "When the scallop attains the size of 8 millimeters 

 the coils of the intestine are inclosed by the visceral mass, or rather 

 are seen to be enfolded in that substance, and are carried ventral as the 

 mass increases in size. The anal opening passes during this development 

 from a position dorsal to the adductor muscle to a more ventral situa- 

 tion in the adult, thus further increasing the length of the digestive 

 tract, which passes through the central chamber of the heart. 



Coloring of the Shell. 



The numerous color variations in the shells of young scallops render 

 them conspicuous among other objects on the tidal beaches. Scallops 

 are found of all shades, ranging from the plain color to the striped 

 varieties, with hardly two alike, and are on this account often gathered 

 for ornamental or decorative purposes. The popularity of the scallop 

 shell is ancient, as history tells us that this shell was the device on tha 



