Oryanization of the Cyprides. Ill 



larynx. It is, however, by no means free, as supposed by 

 that author, but has its larger, hinder j)ortion united with the 

 intestine. Only the smaller, anterior part, embraeed laterally 

 by powerful muscular bands and ventrally attached by mus- 

 cular threads to the endoskeletal plate, lies free in front of 

 the intestine, and is drawn forward by a large pair of muscles 

 originating at the summit of the labrum and running beneath 

 the brain and obli(|ucly over the oesophagus, and backward 

 by a second grouj) of muscles acting in the opposite direction. 

 This forward and backward displacement, which reminds us 

 of the motory mechanism of the gizzard in the Dccapoda, 

 affects only the dorsal wall, the strong convexity of which 

 projects into the lumen, beset with rows of pointed teeth, and 

 acts like a rasp against the concave ventral wall, also densely 

 armed with points. It corresponds with Zenker's " Heibzeug," 

 while the part described by that author as " Ringknorpel " 

 represents the bottom and the lateral wall of the oesophagus. 

 The middle intestine is divided by a deep constriction into two 

 sections, of which the anterior surrounds the throat-like 

 opening of the gizzard and gives off the two hepato-pancre- 

 atic tubes into the interspace of the duplicature of the shell. 

 It contains a very deep glandular epithelium, and must, as 

 the stomach, have the function of digesting albuminous bodies. 

 The second, far longer but equally wide section of the intes- 

 tinal tube, the chyle-intestine, appears chiefly to effect the 

 absorption of the nutritive materials. No muscular rectal 

 section in Zenker's sense is present ; the anal aperture is a 

 narrow fissure concealed by a valve and placed dorsally from 

 the furcal joints. 



5. Secretory organs. — Both the antennal gland and the 

 gland of the second pair of maxillai are well developed in 

 Cyyris^ but it is the former which is removed into the shell- 

 cavity and therefore must be characterized as the shell-gland. 

 Its position and form 1 have already represented correctly in 

 my memoir on the development of Cypris (1868), but witiiout 

 tracing the finer structure. It commences above the entrance 

 of the hepato-pancreatic tube into the cavity of the carapace 

 and allows a terminal saccule to be distinguished from the 

 gland-duct, which is somewhat tortuous, but not folded into 

 convolutions. The cells of the former contain small nuclei 

 and are very intensely stained by reagents. Excretory pro- 

 ducts are often deposited in its lumen. The gland-duct con- 

 sists only of a series of perforated cells, the nuclei of which are 

 of extraordinary size and emit digitiform branches above and 

 beloWj each representing only a single perforated cell. The 



