388 WALTER E. CAMP 



In a newborn fish (27 cm. in length) the gland was found only 

 on the left side. It is very similar in structure to that described 

 in the 'pup.' Many of the tubules have become dilated into 

 large vesicles which communicate with each other and with the 

 smaller tubules. The cranial portion of the gland has also devel- 

 oped into numerous small branching tubules and isolated vesi- 

 cles. Two solid downgrowths of the pharyngeal epithelium are 

 present, one being in the caudal and the other in the cranial 

 portion of the gland. The most cranial one is the larger and 

 is fused with the epithelium of one of the adjacent tubules. The 

 downgrowth in the caudal portion of the gland is small and 

 narrow and is fused with the epithelium of one of the gland 

 tubules in only one section of 10 micra. 



From the newborn to the adult the gland grows considerably 

 in size. Although there is some formation of new tubules, the 

 growth is due chiefly to an increase in size of the individual 

 elements. The majority of the smaller tubules present in the 

 earlier stages have, in the adult, become converted into large 

 thin-walled vesicles which are elongated or irregular in shape, 

 and communicate with adjacent vesicles by constricted necks. 

 A number of the vesicles, especially in the extremities of the 

 gland, are completely isolated. The gland lies embedded in the 

 connective tissue of the pharyngo-pericardial wall, between the 

 ceratobranchial cartilage laterally and the cardiobranchial carti- 

 lage and coracobranchial muscle medially. Some of the most 

 caudal vesicles are flattened in their dorso-ventral axis as a 

 result of being squeezed into the interval between the cartilage 

 and muscle. 



A large diverticulum or invagination of the pharyngeal epi- 

 thelium, similar to that described in the 'pup', is present in the 

 adult gland. It begins at about the level of the middle of the 

 gland and extends almost to its caudal extremity. It is directed 

 obliquely downward and toward the median line and is entirely 

 independent of the gland vesicles adjacent to it. It contains a 

 large saccular cavity, which opens directly into the cavity of 

 the pharynx. A portion of the adult suprapericardial gland has 

 a true duct opening into the pharynx. It consists of a small 



