44 CALIFORNIA ACADEMY OF SCIENCES. 



thorax, sometimes arise from small, circular, uncolored 

 spaces, when they are said to be "pustulated." The 

 last segment is variously elongate, short, with emarginate, 

 truncate or convex posterior margin, which is evenly or 

 unevenly fringed with short to long hairs. The lateral 

 margins of thesegments are usually strongly chitinized, 

 the chitin being sometimes translucent, but usually dark 

 brown to black. 



Internal. — For our present knowledge of the internal 

 anatomy of the Mallophaga we are indebted chiefly to 

 Nitzsch, Kramer and Grosse. Among the points of 

 special interest presented by the internal structure are the 

 concentration of the nervous system and the differing 

 types of crop in the two sub-orders. 



Alimentary Can al (figs, i and 2, plate ii). The oesoph- 

 agus of the Amblycera simply expands widely to form a 

 crop; in the Ischnocera, the crop appears as a conspicu- 

 ous diverticulum or lateral sac of the oesophagus. The 

 crop often bears spines or teeth on its inner wall. There 

 are two pairs of salivary glands, variously cylindric, 

 clavate, sub-spheroid, reniform, or divided into many 

 small cylindrical tubes. The stomach usually presents 

 two forward-projecting sac-like expansions. There are 

 four thread-like, unbranched, Malpighian tubules. 



Genitalia (figs. 4 and 5, plate ii). In the male there 

 are paired testes, two sperm-ducts uniting to form an 

 ejaculatory duct, accessory glands and a protrusible penis, 

 with chitinized, often elongated, side-pieces. The female 

 has paired ovaries ("three pairs of ovarian tubes in 

 Liotheidae, five pairs in Philopteridae "), two oviducts 

 uniting before issuance, and a seminal receptacle (called 

 by Nitzsch " Kittdruse," but by Kramer and Grosse a 

 receptaculum seminalis). 



Dorsal Vessel. Kramer found the heart of Lifeurus 



