Cooley 8c Kohls: Argasidae of N. America, etc. 



OrNATE: Ornate ticks are common in Dermacenior and Ambhwmma which have a 

 symmetrical pattern of color usually spoken of as "white" or "gray, - "rose- 

 tinted," etc., superimposed over the base color of the chitin. In the Argasidae 

 ornamentation is lacking except in O. coriaceus in which the mammillae are 

 crowned with "white," "cream," or faint iridescent colors. 



PANDURIFORM : Obovate, with a concavity on each side, like a violin. 



PosTPALPAL Hairs: A pair of hairs placed posterior to the palpi, more or less in 

 line with the posthypostomal hairs. 



Posthypostomal Hairs : A pair of hairs on the ventral surface at the base of the 

 hypostome. 



Sex Opening: The external evidence of the sexual organs of either sex found on the 

 ventral median line posterior to the capitulum. 



Similar: The sexes are similar if separable only by size and the differences in the 

 morphology of the sex openings, and dissimilar if there are other morphological 

 differences of the body or appendages, as in Antricola coprophilus. Adults and 

 nymphs are similar if separable only by the presence of the mature sex openings 

 in adults which are absent in nymphs, and dissimilar if, as in Oiobius, the 

 adults and nymphs have differences in body structures. 



Simple Hairs: Smooth, tapering hairs which terminate in a point. 



Spiracle: Paired organs, one on each side; the external openings of the respiratory 

 system which communicate with the tracheae. 



Subapical Dorsal Protuberance: The protuberance sometimes present distad of 

 Haller's organ and when much drawn out produces the bifurcate termination 

 of the tarsus, mentioned by some authors. It should be distinguished from dorsal 

 humps. The protuberance appears to be different in origin or purpose from the 

 dorsal humps. Thus, the species of Argas and those species of Ornithodoros 

 which have cheeks, and micromammillae on the legs seldom have dorsal humps, 

 but may have the subapical dorsal protuberance. Fig. 1, D and E.. 



SuTURAL LlNE: A definite line of cleavage around the periphery in Argas separating 

 the dorsal and ventral surfaces. Fig. 2, D and Fig. 4, G. 



TUBERCLES: The elevations on the integument in Anlricola comparable to the mam- 

 millae of Ornithodoros. 



Truncated Hairs: Hairs which do not taper and are terminally truncated. 



VENTER: The entire ventral surface in contra-distinction to the dorsum. 



Methods 



The characters in the Argasidae are definite and little difficulty should be 

 encountered in recognizing most species. The methods of study here outlined 

 are applicable also to various genera of the Ixodidae. 



Dissecting microscope. — A primary need is a satisfactory dissecting micro- 

 scope with low, intermediate, and high power objectives. Very satisfactory 

 types are: first, one with a stage that can be placed directly on the surface of 

 the desk; second, one with a heavy base placed well away from the worker and 

 with a horizontal arm supporting the body of the microscope, thus leaving a 

 clear working space around and under the instrument. 



Lighting. — Adequate lighting is about as necessary as a suitable micro- 

 scope. Desk and microscope lamps of numerous forms are available but a type 

 producing a bright beam and on a stand which can be placed well away from 

 the microscope is particularly useful. It should be possible to adjust the inten- 

 sity of the light and to avoid heating the specimen. Both aims can be accom- 

 plished by placing a piece of rice paper or ground glass in the beam of light. 



