306 Prof. Westwood on 
female Doreus derelictus,* may be the opposite sex of Rhe- 
tus, whilst at the same time he entertains the opinion that 
Dorcus rudis, Westw., is the female of the insect described 
below, under the name of Dorcus ratiocinativus. I have 
entered into the consideration of this opinion, in the 
observations upon D. rudis, given in a subsequent page. 
In his original description of D. derelictus, Major Parry 
was so struck with the “ utterly anomalous slender anterior 
and unarmed posterior tibive,’’ and other characters, as 
to doubt whether the specimen were really a female, or a 
male with short ill-developed mandibles, and whether 
the insect ought not to be removed to the genus Hury- 
trachelus; whilst in his memoir, in 1870, he considered 
it nearer to Cladognathus and Odontolabis. The speci- 
men having been dissected by Mr. C. Waterhouse, has 
proved to be a female, as confirmed by a subsequent 
examination of the mouth-organs, which I have been 
enabled to make by the kindness of Major Parry, and 
which are noticed in my observations on the sexual 
relations of D. rudis. 
Dorcus RATIOCINATIVUS, nN. 8. 
(Plate VIII. fig. 2, wale.) 
Niger, prothorace et elytris parum castaneo-tinctis, 
capite opaco pone oculos subangulato, mandibulis capitis 
longitudine, falcatis dente medio suberecto armatis, pro- 
thorace transverso quadrato, lateribus subparallelis, angu- 
his posticis lateralibus truncatis, denticulo parvo utrinque 
instructis, pronoto et elytris subnitidis et subleevibus. 
Long. corp. lin. 11; mand. fere lin. 2. 
Hab.—Himalaya. In Mus. Parry. 
This small species is of a narrow oblong form, the 
thorax being scarcely broader either than the head or 
* Dorcus derelictus, Parry. 
Proc. Ent. Soc. Lond. 1862, p. 112; Trans. Ent. Soe. 3rd, s. v. 2, 
pp. 50, 90; 1870, p. 92, pl. xi. f. 3. 
D. elongatus niger nitidus, capite inter oculos bituberculato; mandibulis 
obsolete unidentatis; elytris levissimis subparallelis ; tibiis posterioribus 
extus subcurvatis, Inermibus, intermediis unidentatis. 
Long. corp. (mand. incl.) une. 1, lin, 5. 
Hab.—Ind., or Himalayas. Coll. Parry. 
