14 



Psyche 



[February 



which projects well beyond the spiracles and is slightly emarginate 

 at the tip. The actual number of segments cannot be determined 

 from the mounts, but there are in all nine transverse series of pos- 

 teriorly pointing denticles. The anteriormost series is close to the 

 anterior end of the body and is composed of very small denticles. 

 The second to fourth series are each composed of a single row of flat 

 denticles, the points of which are directed toward the median line 

 and end in a recurv^ed hook (Fig. B). Between each two of these 



Fig. 1. Cuterebra americana, first stage: A, entire larva only the bases of the 

 tracheal trunks are indicated; B, denticles from third series at the median line; 

 C, denticles from fifth series. 



denticles are smaller sharply pointed denticles and behind them 

 are a varying number of still smaller, sharp denticles. The re- 

 maining series are all composed of numerous sharply pointed denti- 

 cles, of which the anteriormost are much larger than the others 

 (Fig. C). The cephalopharyngeal apparatus extends back to the 

 anterior margin of the third series. 



Note. — The above description is based upon specimens that have 

 been cleared, stained and mounted on a slide. 



