ON THE DEVELOPMENT OF DERMATOBIA HOMINIS. 495 



Blanchard says specifically that the stigmal plates were not apparent although one 

 can see them indicated in his own figure of this stage (Blanchard, '92, p. 137, Fig. lOe) . 



2. Matas' Larvae.— Through the kindness of Dr. L. O. Howard, United States 

 Entomologist, Washington, D. C, the two specimens from the case of Matas ('87), 

 which are now in the collection of the United States National Museum, were loaned 

 me for examination. One of these was evidently the one figured in the original paper 

 (Matas, '87, p. 166) and also in the excerpt in the first volume of "Insect Life" (p. 79). 

 There are, however, a number of flocculent masses of coagulated pus adherent to the 

 surface , and the body has a sharp bend at the point of transition from the segmented 

 anterior portion to the smooth, attenuated posterior portion. Both these features 

 contribute to give the specimen an unnatural appearance which is even heightened 

 in the figure by the method of reproduction employed, so that one might question 

 the agreement of the larva represented in the figure with the form under consideration 

 in this paper. The following notes will make the character of the Matas' specimens 

 clear. 



The larger one, that mentioned above, measured 2.2 millimetres in breadth at the 

 fifth somite by 9 millimetres in length; about two-thirds of the length is occupied by 

 the smooth unsegmented posterior region, a proportion which seems unduly large. 

 This may have been caused by the inordinately thick skin of the gluteal region of the 

 host from beneath which the parasite was extracted by Matas. The specimen makes 

 a sharp angular bend ventrad just behind the last complete row of hooks, which may 

 have led to the error of Matas in estimating the length at 5 millimetres. 



The various types of hooks are in agreement, both as to size and arrangement, with 

 those already described for the smallest larva of my series. One notes at once the 

 cheek and chin patches of minute hooks on the first somite, the bands of small hooks 

 on the second, third, and fourth somites. The anterior row on the fourth somite, 

 which was noted as composed of larger hooks than those in the rest of the band, is 

 even more prominent in this specimen than in my own and suggests more distinctly 

 the conditions of the subsequent somites and also of later stages in development. 

 The complete and incomplete rows of large hooks are similar in position and number 

 to those of the larva mentioned above; they contain the following numbers of hooks: 



Numbers of Hooks. 



Number of Somite. Character of Row. Right. Left. Total. 



IV Incomplete 9 9 18 



V Complete 15 15 30 



Incomplete 9 8 17 



VI Complete 11 13 24 



Incomplete 6 7 13 



' VII Complete 11 11 22 



