342 EDWARD S. MORSE ON 



In tlie Lingulidae, the mitrinit caiiiil lias a definite pharj'iix, oesophagus, stomach, 

 and gut. In Glottidia the nioutli, as seeu from below, is marked by very prominent hps; 

 these are everted, the lower lip turning backward and at times being widely cUstended ; 

 the upper lip showing a continuous curve, the lower lip divided by a deep median 

 depression or thrown into four folds, as shown in 50: o, 4. 



The lips are very sensitive and mobile, and are a continuation of the brachial fold 

 which runs the entire length of the coiled brachia. The strong ciliary movements of 

 tlie cirri sweep the microscopic organisms, upon wliich the animals subsist, along this 

 groove and directly into the mouth. These parts in Glottidia and Lingula are colored 

 lirowii. The mouth and pharynx stand quite free from the anterior wall, as may be seeu 

 in the various longitudinal sections figured (47: "i; 50: 1,2). The extreme mobility of 

 the brachia and the delicate movements of the lips and bracbial fold justify the belief 

 that when the young forms are observed the mouth parts will show great freedom of 

 motion. 



A longitudinal section of the pharynx in Glottidia reveals on its upper inside surface 

 three transverse areas of irregular depressions (50: 0), the ridges separating these 

 depressions being sharp and conspicuous. This structure suggests a triturating apparatus, 

 as the lower floor of the pharynx is smooth and the folds of the stomach and intestine 

 are longitudinal. An external view of the dorsal portion of this region shows longitu- 

 dinal muscle fibres diverging anteriorly and two distinct sets of transverse muscles which 

 are evidently connected with the triturating surface of the pharynx (50:5). The 

 pharynx and oesophagus ascend sharply to the stomach (47: 2; 50: 1, 2) . The anterior 

 portion of the stomach is globular with a slight constriction Ijehind and then an abrupt 

 dilatation forming a sharp collar which becomes abruptly constricted as it enters the intes- 

 tine. To this collar are connected the gastro-parietal band and other membranes below, 

 makino- a partition which almost separates the perigastric cavity from the peri\'isceral 

 cavity. A section of the stomach of Glottidia shows the interior membrane thrown into 

 folds. The intestine follows the same general course as in Lingula, which has been 

 repeatedly figured ; it differs from Lingula, however, in the slight flexure seeu in the first 

 leniJ-th that turns forward (47 : l) . The figure shows this portion of the intestine removed 

 to one side in order to expose the nephi-idium below. The intestine within is clothed 

 with a ciliated epithelium. 



In Lingula lejndKhi, the pharynx and oesophagus are longer than in Glottidia and 

 nuiy be elongated or shortened by the contraction of certain muscles as already described. 

 In a retracted state (47: 4), the pharynx is slightly bulging, and on each side may be seen 

 sniidl, round glands which occupy precisely the same position that they do in certain 

 chaetopods. I have therefore called these bodies pharyngeal glands. They doubtless 



