232 Description of a Species of Caligus. 



The lateral and anterior margin of the buccal mass is formed 

 by a slender bone, (c b, fig. 12,) which forms a projection posteri- 

 orly where it suddenly curves around inward, and runs backward 

 a short distance nearly parallel with the margin. These bones 

 form the sides to the lower membrane of the cavity of the mouth. 

 At the anterior extremity of the buccal mass within, they are 

 connected with several small bones which run to the medial line 

 of the mouth, and constitute part of its manducatory apparatus, 

 (m, 1, and n, fig. 13, r, s, t, fig, 17, an under view ;) these bones 

 lie either on or in the lower membrane of the mouth. No portion 

 of the upper membrane of the buccal mass is connected with the 

 bones of the lateral margin except a small subtriangular piece 

 near the anterior angle, (dae, fig. 12.) These pieces leave be- 

 tween them and the anterior margin of the buccal mass a semi- 

 circular opening ; the edges of this opening are fiurnished with 

 cilias, and constitute the lower margin of the lunar opening, or 

 the loiver lip. This lower lip is divided at its centre, (b, fig. 12,) 

 and the edges thus fonned are curved inward, so that in a vertical 

 view several ciliae are pi:ojected together, and have the appearance 

 of one branching cilia. 



The whole membrane forming the upper portion of the buccal 

 mass may be called the upper lip. It .is represented separate in 

 fig. 15. It is united with the lower portions, at its posterior ex- 

 tremity, (pp, figs. 12 and 15.) It may be viewed as consisting 

 of two parts, an anterior movable, and a posterior, apparently 

 immovable. The movable portion, which is very much the 

 smallest, is an elliptical, nearly circular, membrane, inserted in a 

 semicircular concavity (a a) in the anterior margin of the immova- 

 ble portion. Its front edge is coarsely subcrenated and furnished 

 with ciliae. The large immovable portion of the upper lip is 

 bounded by a bony edge, on all sides except posteriorly. At f, 

 (figs. 12, 15,) there is a curved process elongated outward, serv- 

 ing for the attachment of a muscle. 



Through the opening between the lips, (fig. 12,) we liiay ob- 

 serve the two slender bones 1, (fig. 13,) and just within these, there 

 are visible, through the membranes, two dentated organs, which, 

 when the membranes above are removed, appear as represented 

 in fig. 14. These organs are the ma^idibles. They are long 

 slender organs with a falciform termination, ciu-ved inward and 

 dentated on the interior edge ; the number of teeth is about 



