1903.] NATURAL SCIENCES OF PHILADELPHIA. 367 



Alimentary tract.— The large cavity (PL XVIII, Inf., figs. 1-3) of 

 the corona opens externally by the ventral mouth (coronal aperture). 

 It is without ciha and hned by a continuation of the hypodermis and 

 its cuticula. It is succeeded by a thick-walled short oesophagus 

 (Pi. XVIII, Oes., fig. 1), also without cilia and \nth a sphincter muscle 

 (as Gast has described.) From the oesophagus, and attached to its 

 posterior end, a narrow flexible tube (PL XVIII, Oes.T., figs. 1-3) 

 extends back into the proventriculus, which may be termed the oesopha- 

 geal tube (this was also described by Stokes for A. hucinedax). This 

 tube is hned by a thin epithehum with a few nuclei, and its posterior 

 shghtly enlarged end is free; it is laterally compressed, and probably 

 possesses a musculature of its own, since it beats in rapid undulations 

 with many changes of form ; it is very elastic to ahow the passage of 

 the large objects of food (mainly smaller free-swimming Rotatoria, also 

 Ostracoda, Nematoda, Infusoria and Acarina). The proventriculus 

 (Prov.) is a large, distensible sac, of nearly the width of the trunk; its 

 interior surface is hned by a cuticula without cilia, next fohows a clear 

 zone of transparent protoplasm, then the peripheral cytoplasmic layer 

 containing the nuclei. The musculature of this region described by 

 Gast I was unable to find. The mastax Ues at the posterior end of the 

 proventriculus; its appearance is shown in fig. 1, and the masticating 

 teeth of one side shown in fig. 5; I have not been interested to deter- 

 mine its finer structure, which has been done very carefully by Gast, but 

 will simply state that its large tooth is not sharply bent at the tip as in 

 lentiformis, and that of the four smaller teeth on each side one is fre- 

 quently absent. Further, the usual parts may be distinguished: the 

 unci and manubria, the fulcrum and its rami. On this follows the 

 stomach proper (Chylusdarm, Mecznikow; oesophagus, Foulke; stom- 

 ach, Leidy; Magendarm, Gast). This (PL XVIII, Stom., figs. 1-3) is 

 the only portion of the tract that is ciliated, and it is the assimilative 

 portion of the intestine, with a single epithehum of large nucleated 

 cells containing fatty globules. The posterior intestine {P.Int.) is a 

 wide sac lined by a flat nucleated epithehum, which opens into the 

 dorsal side of the cloaca (CI., flgs. 2, 3), a distensible tube hned by a 

 similar epithelium. The cloacal aperture {Cl.Ap.) is surrounded by a 

 sphincter muscle (found by Gast) and is actually ventral, but morpho- 

 logically dorsal since it is behind the foot. 



The only glands of the intestine are one pair of large stomach glands ; 

 these {Stom.GL, figs. 1-3) are pyriform with long ducts, the body of 

 each gland placed at the ventro-posterior margin of the posterior intes- 

 tine, the duct curving up around the dorsal margin of the intestine to 



