1919 Fasten; on Salmincola 157 



antennary gland, and then traverses downward through the cavity lying 

 back of the second maxillae (Fig. 17 s. g). The gland itself resembles 

 a kidney in shajDC, and near the second maxilla it gives off a slender duct, 

 which opens to the exterior after traversing the maxilla. The maxillipedal 

 glands are somewhat bean-shaped and are situated behind the maxillipeds. 

 They give off tubular ducts which make their way into the maxillipeds 

 and there open to the outside. 



Aside from these distinct glands there are numerous glandular cells 

 located near the pharynx (Fig. 16, ph. g), which probably secrete enzymes 

 useful in digestion. These cells are pear-shaped in character and possess 

 prominent nuclei. 



d. The muscles of the first copepodid larva are numerous, striated 

 and well developed. Those which can be easily distinguished are: (1), 

 the dorsal muscles (Figs. 1, and 18 to 20, m), running along the dorsal 

 surface of the cephalon and first thoracic segment, and functioning in the 

 operation of the abdomen; (2), the lateral muscles (Figs. 1, 11, 19 and 

 20, 1), extending along the lateral margins of the first thoracic segment, 

 and functioning in the movement of the second thoracic segment; (3), the 

 muscles which operate the first pair of swimming feet (Figs. 1 and 11, m'), 

 and are located in the lower lateral extremities of the first segment of 

 the thorax; (4), the muscles which operate the second pair of swimming 

 feet (Figs. 1 and 11, m"), and are located along the sides of the second 

 thoracic segment; and (5), the dorsal abdominal muscles (Fig. 1, ra'"), 

 which aid in the movement of the abdomen. There are also a great many 

 smaller muscles within the segments and appendages, but these could not 

 be accurately traced. Connected with the foot of the attachment filament 

 are numerous thin muscle strands (Figs. 24 and 25, ft. m), which operate 

 in the discharge of the attachment filament from the body of the copepod. 

 These muscles surround the bulla (Fig. 25, ft. m), originating below the 

 extreme anterior surface of the cephalon and then passing downwards 

 to become inserted in the foot of the attachment filament. One might 

 easily overlook these muscles, for there are so many other structures 

 crowded into the region where they are located. It was only after pro- 

 longed and careful study of a great number of larvae that these interesting 

 muscles were discovered. 



e. The digestive system is very difficult to trace by an examination 

 of the entire organism. When thus studied the copepod is found to be so 

 clearly transparent that the digestive system appears to be only partially 

 developed, consisting of a large central cavity filled with yolk globules 

 (Fig. 1, y), while the anterior and i)osterior jjortions of the gut seem to 

 be lacking. The true nature of the digestive system, and for that matter 

 of the entire internal anatomy of the first copepodid organism can only 



