286 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



O. L. Cartwright, B. K. Dozier, C. A. Frost, M. Robinson, F. N. 

 Young, and the writer. 



Variation in size is considerable, ranging from 16 to 22 mm. in 

 length and from 10.5 to 14.5 mm. in width. Sexual differences have 

 already been noted in color, depth of striae and punctures, and in the 

 male modifications of the foretibia and hind femur. In the males the 

 row of irregular teeth on the underside of the foretibia is composed 

 of from 3 to 7 teeth which are usually somewhat longer than those of 

 profundus or dubius. While there is general uniformity in the lack 

 of a double line of punctm^es behind the median anterior pronotal 

 margin, there is often a suggestion of a V-shaped tubercle, noted 

 in Peltotrupes profundus dubius. This tubercle is never as pro- 

 nounced as that of dubius, nor does a double row of punctures run 

 on either side of it as is the case in dubius. The anterior pronotal 

 angles exhibit such variation that their usefulness as a distinguishing 

 characteristic is slight. Depth of striae and punctures also show 

 some variation, but seldom approach the degree of development noted 

 in profundus or dubius. The greenish iridescence is quite constant, 

 but its extent is varied, being much more evident in the males. Other 

 differences in morphological characteristics noted are slight. 



The obsolete elytral striae indicated by the rows of small punctures, 

 the very obtuse angle (pi. 2, fig. 4a) anteriorly between normal con- 

 vexity of elytra and beginning of elytral margin, and the green irides- 

 cent color usually readily separate youngi from either profundus or 

 dubius. Other differences are the sparse thoracic punctures, and the 

 posteriorly curved inner edge of the anterior margin of the pronotum, 

 which lacks the sharply defined tubercle of dubius (pi. 2, fig. 3a). 



The known range of this species is very restricted, being confijied 

 to a small isolated sand ridge south of Interlachen, Fla., which was 

 discovered and carefully described by Frank N. Young. This species 

 has been named after Dr. Young in appreciation for his interest and 

 the help that he has given me. 



The biology of this species is better known than the other species 

 of Peltotrupes, having been discussed by Young (1950) under the 

 name chalybaeus and by Howden (1952) under the name profundus. 



To my knowledge, nothing of importance since these papers has 

 been added to the known facts of the habits of this interesting species. 



The adults, which occur from January to April, are colonial and 

 deep burrowing, and confine their surface activity to the hours of 

 darkness. Adults are readily attracted to decaying fungi, malt, or 

 molasses, and even banana peels and propionic acid. No evidence 

 was seen of their feeding on dung, but it is quite possible. 



The burrowing activities of the adults are amazing, both in the 

 number of burrows in a restricted area (pi. 17, fig. 2) and in the depth, 



