Mr. J. Nietner on new Ceylon Coleoptera. 1 75 



objects, by far the greater number are limited to tropical seas, 

 A notion seems to prevail that the floating species are also 

 almost entirely natives of the warmer-temperate and tropical 

 regions of the ocean, and that specimens picked up in northern 

 regions are wanderers that have been carried beyond their 

 proper range. It is desirable to ascertain to what extent this is 

 the case. 



Edinburgh, July 17, 1858. 



XVIII. — Descriptions of new Ceylon Coleoptei'a. 

 By John Nietner, Colombo, Ceylon. 



[Continued from vol. xx. Ser. 2. p. 375.] 



Family CARABID^. 



Tribe Trigonotomid^. 



The Trigonotomidse with an elliptic terminal joint of the jjalpi 

 are abundantly represented amongst the Ceylon Carabidfc, thus 

 making amends for the want of other tribes of the section to 

 which they belong. I have now before me a great many indi- 

 viduals of different species which I have endeavoured to distri- 

 bute into genera, after the works of Lacordaire, Dejean, and 

 others of less importance. A single glance almost convinced me 

 that they must belong either to Abaceius, Distriyus, or Drimo- 

 stoma, — genera closely allied, and whose principal, in fact only 

 essential, distinction would appear to consist in the shape of the 

 mentum-tooth. If it is a well-established fact, as cannot be 

 doubted from the above authors, that this tooth is pointed in 

 Drimostoma, — large, rounded, equalling the lateral lobes in Aba- 

 cetus, and large and truncated in Distrigus, the species described 

 below could not, as to their genera, be distributed otherwise than 

 I have done, — namely five to Distrigus and one to Drimostoma. 

 The species which I have drawn to the former genus have a 

 large, more or less square tooth, slightly rounded at the anterior 

 angles. It is impossible to call this tooth pointed in any of the 

 five species ; they cannot therefore belong to the genus Drimo- 

 stoma ; nor can any of them be drawn to Abacetus, which genus 

 is, moreover, apparently exclusively African. As to the insect 

 which I have placed in the genus Drimostoma, its mentum-tooth 

 is not exactly pointed, but it is altogether narrower than in 

 Distrigus, and might well be called "assez aigue,^^ as Dejean 

 describes it. This insect differs, moreover, very materially in 

 general appearance, as well as in its details, from my Distrigi ; 

 and I feel sure that it belongs to the genus in which I have 

 placed it, although it docs not quite agree with Lacordaire's 



