56 Transactions of the 



same light as Dr. Cobbold, as being probably an excretion of the 

 inner cellular layer, which consists of small granular-looking cells. 



Immediately beneath the integument is a thick layer of longi- 

 tudinal muscles. The muscular fibres (Plate LXXV., Fig. 3) are 

 about 5-ioth of an inch in diameter, non-striated, nebulous, and 

 occasionally exhibit nuclei at intervals. They are dissolved rapidly 

 by moderately strong acetic acid, and, like all the tissues of the 

 Ascaris, are very elastic. 



I have been unable to detect any transverse layer of muscle, 

 although Cloquet has described such a layer, and I suspect with Dr. 

 Cobbold that the annular striation of the integument has given rise 

 to the opinion that such a layer exists. 



The mouth is surrounded by three Hps, emarginate in front 

 (Fig. 4). The external chitinous layer of the integument is con- 

 tinued into the thick muscular pharynx, which it lines. It is thrown 

 into three ridges which alternate with the lips (Fig. 5), and which 

 are covered with sharp-pointed tubercles, forming three very effec- 

 tive pharyngeal teeth. Fig. 6 represents the rounded anterior 

 extremity of one of these ridges. The exterior of these ridges, 

 which are prolonged to the posterior extremity of the pharynx, 

 gives attachment to the transverse muscular fibres of the pharynx, 

 so that these are divided into three sets. 



Several shghter ridges run transversely across the main ridges, 

 and probably give attachment to some of the numerous longitudinal 

 muscular fibres of the pharynx. The fibres of the pharynx are less 

 than half the diameter of those of the body waU, but are, like them, 

 non-striated. 



I have been unable to detect any muscle in the ahmentary 

 canal below the pharynx, which appears to consist of an external 

 chitinous layer lined with epithelium. In this respect it is precisely 

 like the inner layer of the intestinal canal of an insect. I strongly 

 suspect that the rough surface of the ridges of the pharynx is 

 epithelial, and that the pharynx is elsewhere lined with epithehum 

 similar to that in the remainder of the intestinal canal, but I have 

 been unable to observe this satisfactorily. 



I would point out some remarkable afl&nities with the abranchiate 

 annehda, exemplified in the three pharyngeal teeth and the seg- 

 mentation of the integument, which is very similar to that in the 

 leech : these seem to indicate a closer affinity than has hitherto 

 been recognized. 



One of the first points which attracts the attention of the most 

 casual obsei'ver in the external appearance of Ascaris is the presence 

 of four longitudinal white or pinkish lines or bands running the 

 whole length of the animal. These have been incorrectly described 

 by numerous observers as muscles, and Dr. Cobbold has fallen into 

 the singular error of speaking of them as the " only muscles in 



