18 



G. o. sars. 



[No. 1. 



their insertion at the middle of the scape, some at the base ot 

 each branch. The muscles of the branches are arranged in two 

 longitudinal rows, one along the upper and one along the lower 

 edge, and extend to their apex. 



The anterior lip, or labrum (Pl. III, figs. 3, 5. L) 1 con stitut es 

 a rather large fleshy lobe, forming the immediate continuation 

 of the lower surface of the head, and projecting backwards so 

 as to cover inferiorly the masticatory parts of the mandibles» 

 It admits, however, of being removed from the oral parts or being 

 lowered to a certain extent by the aid of two slender muscles 

 issuing from the skin of the head just behind the eye and 

 running obliquely back to its base. In a lateral aspect (fig. 5. i), 

 it appears rather narrowly oblong and slightly curved, with the 

 lower side evenly vaulted, the upper somewhat expanded and 

 concave. To its extremity, a small compressed lamella of a 

 somewhat securiform shape is movably attached, being defined 

 inferiorly from the body of the lip by a distinct incision. Seen 

 from below (fig. 4, L), the body of the lip exhibits an elongate 

 quadrangular form, with the lateral edges somewhat expanded pos- 

 teriorly and converging to an obtuse point, below which the 

 terminal lamella juts out as a narrow projection. The upper 

 surface of the lip is channeled along the middle, the channel 

 being limited by a soft, finely ciliated skin, forming the immediate 

 continuation of the lower wall of the æsophagus. Within the 

 body of the lip some large cellular bodies, apparently of gland- 

 ular nature, are found to occur, partly concealed by numerous 

 delicate muscular bundles passing across the lip from the lower 

 to the upper surface. 



The mandibles (fig. 4, 5, M) form a pair of rather large and 

 highly chitinized bodies, encompassing the sides of the head at 

 the junction between the preoral and postoral parts, being, however, 

 more properly referred to the latter. As in other adult Pbyllo- 

 poda, they exhibit no trace whatever of palps, consisting each 

 (Pl. IV, figs. 2, 3) of an oblong navicular body produced at the 

 lower end into a strongly incurved masticatory part. The body 

 is evenly convex exteriorly, whereas on the inner side it is deeply 



