NATURAL HISTORY OF THE BAY SCALLOP 
589 
of the principal functions is to rotate the food material received from the oesophagus 
and so aid mechanically in the sorting of food and that an important amount of food 
material may be caught up by the style and returned to the stomach. In addition, 
this stirring of the food by the style with the continual dissolving of the head of the 
style would seem ideal for mixing the enzyme of the style with the food material. 
I have not noted a scallop freshly killed soon after removal from the water 
which did not possess a style. A special search of scallops in poor condition has not 
been made. 
Nearly surrounding the stomach is a mass of tissue which in P. ir radians is of 
a dark green color. Earlier writers termed this liver or hepato-pancreas. Dakin, 
(1909) who studied the contents of this tissue (Pecten) and found that an extract 
would digest proteids, starch, and fats (that is, contained amylase, protease, and 
lipase), naturally assumed that these substances were discharged into the stomach to 
prepare the food for absorption by the intestine, and gave the name digestive gland. 
Yonge (1926a) working with 0. edulis, con- 
cludes that these substances are not so 
discharged but that the function of the 
organ is intracellular digestion, and em- 
ploys the term “digestive diverticula,” 
which is here adopted. “ Circumstomachal 
organ” or “circumstomachal tissue” 
would be reasonably definite as to desig- 
nation and noncommittal as to function. 
The intestine of scallops, as figured by 
Drew, Dakin, and Belding, is a short affair 
scarcely more convoluted than that of an 
oyster. In local specimens, dissection and 
sectioning reveal a long intestine with 
several convolutions within the visceral 
mass (figs. 10 and 11), as does examination 
of free-hand sections of a specimen from 
Massachusetts. The style sack or CEecum connects by means of a narrow slit 
with the food passage, which it greatly exceeds in cross section. (Fig. 9 h.) 
Typhlosoles are large and distinct, (filiation, general throughout the intestine, is 
especially heavy in the style sack. The intestine, leaving the visceral mass, passes 
along the right digestive diverticula and, as the rectum, through the pericardium and 
ventricle, thence around the adductor muscle nearly to the tip of the visceral mass 
where it ends in a trumpet-shaped anus. 
FOOT 
The small, roughly cylindrical foot of the adult scallop (figs. 3 and 11) is useless 
for locomotion. In it is located the byssal gland that secretes the byssus by which 
the scallop attaches itself to eelgrass or other objects. Attachment is more common 
with juvenile scallops but sometimes is practiced by mature or nearly mature indi- 
viduals. It is interesting to note that an European species, P. varius, retains the prac- 
tice of byssal fixation throughout life and even moves about by renewing and slightly 
shifting the point of byssal attachment (Fischer, 1867). It has been suggested by 
Dakin (1909) and claimed by Uexkiill (1912), for whom a rudimentary organ can not 
exist, that the deeply grooved, suckerlike tip of the foot is employed in the removal 
Figure 11.— Sketch showing alimentary canal with much 
convoluted intestine in situ with other parts. A, Anus; 
I, intestine; K, kidney; M, mouth; 0, ovary; St., stomach; 
and T, testis 
