66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



magen (Lindeman) only. In the following discussion the interpreta- 

 tions of Hopkins of the terms crop and proventriculus are used. 



The proventriculus consists of eight plates arranged to form a 

 tube, as illustrated in figure 35. On each plate two longitudinal divi- 

 sions are clearly defined. Lindeman called the cephalad part the Plat-' 

 tenteil (A), the caudad part the Ladenteil (K) ; the corresponding 

 terms of Hopkins are anterior plate and posterior or masticatory 

 plate. The latter terms are adopted in this paper. In Gnathotrichus, 

 both of these plates are divided by a median suture (a) which is dis- 

 tinctly visible on the masticatory plate and indicated by a row of 

 bristles (b) on the anterior plate. These bristles, which are of taxo- 

 nomic importance, have been called Zaehne am medianen Kauplatten- 

 rand by Nuesslin and sutural teeth by Hopkins. In Gnathotrichus 

 they are present as slender, sharply pointed, and simple bristles. The 

 anterior plate is not quite one-sixth as long as the whole proventriculus. 

 The masticatory plate (A) bears a symmetrical arrangement of teeth 

 which presents the true chewing apparatus of the proventriculus. On 

 each tooth two elements are clearly defined, the instep and the den- 

 tation. The totality of the insteps corresponds to the Abdachung (c) ; 

 that of all dentations to the Buerste (a) of the German authors. Hop- 

 kins called the first mentioned the femora of the masticatory teeth, 

 the latter the masticatory brush. The masticatory teeth are all similar 

 in shape and very numerous in the genus Gnathotrichus. Cephalad, 

 they are bordered by a few (8-12) longer teeth (c) which dififer 

 greatly in shape and which are directed toward the center of the 

 proventriculus. These teeth are apparently intended to regulate the 

 entering of the food. They have been called Sperrborsten by Nuess- 

 lin and closing teeth by Hopkins. To distinguish them from a similar 

 arrangement of teeth which occur in Gnathotrichus and other genera 

 on the caudad end of the masticatory plate (f) it is proposed to call 

 the former cephalad closing teeth, the latter caudad closing teeth. In 

 Gnathotrichus, the following armatures are not present : 



(a) Hackenzaehne (Nuesslin), or apical teeth of the anterior plate; 



the designation of a row of short, often curved teeth on the 

 apical margin of the anterior plate. 



(b) Ersatzperrborsten (Nuesslin), marginal bristles or marginal 



fringe (Hopkins) ; a longitudinal row of bristles along the 

 lateral margin of the anterior plate. 



(c) Kreuzlinie (Nuesslin), a row of short, stout teeth arising from 



the lateral margin of the anterior plate and converging pos- 

 teriorly. 



