148 CALIFORNIA ACADEMY OF SCIENCES. 



at one place. An extreme example is shown in the 

 terga of the anterior abdominal segments of Eurymeto- 

 pus taurus. Here the chitin shows in longitudinal sec- 

 tions a large oval thickening near the anterior end of the 

 segment, back of which it forms only a thin superficial 

 plate reaching to near the posterior end. Anteriorly it 

 terminates in a deeper but very short prolongation. 

 The non-chitinized part in front is folded into a strong 

 S-shaped band, the upper loop of which, forming the 

 posterior border of the segment in front, projects over 

 the anterior end of the chitinous thickening. Pro- 

 cesses of the chitinous wall often extend into the body- 

 cavity, especially in the thorax, giving attachment to 

 various muscles. The antennary fossae of the Ambly- 

 cera are formed by chitinous processes from the lateral 

 ventral margins of the head extending outward beneath 

 the antennae, and by a prolongation of the outer dorsal 

 aspects of the head outward and downward (plate xii^ 

 figs. 1 and 2). Chitinous genital parts w411 be de- 

 scribed under the head of the Reproductive Organs. 



The Appendages. — The antennae are three to five- 

 jointed. In the Amblycera they are concealed in deep 

 fossae on the lateral ventral aspects of the head, and 

 generally have the terminal segment enlarged. In the 

 Ischnocera they are simple, filiform and exposed. 



The mouth-parts have already been described in 

 detail in Kellogg's "New Mallophaga, II,"* and merely 

 a general account of their structure will be given here. 

 They are of the biting type and consist of mandibles, 

 maxillae, and labium. The maxillae (plate x, figs. 5, 6, 

 11 and 12) are large, strong, triangular, two-toothed 



* Proc. Cal. Acad. Sci., 2iid Ser., Vol. VI, 189fi. 



