of Dytiscida Darwinians. 7 



and fourth from the suture longest and most strongly marked ; 

 between each of these is another irregular wavy line, and about 

 three externally between them and the margin, the whole anas- 

 tomosing more or less, so as to present a very irregular and 

 imperfect system of reticulations ; there is an abbreviated black 

 line upon the truncate apex next to the suture ; the lateral mar- 

 gins are broadly immaculate, and the usual striae scarcely to be 

 detected. Body beneath dark, the thorax and breast black, the 

 abdomen fuscous. Legs pale yellow. 



The singular thorax of this insect, distinguishes it from all the 

 other species with which I am acquainted. 



Since this paper was communicated to the Society, Mr. Curtis 

 has published a description and figure of what appears to be the 

 same insect as that now before us, in the Transactions of the 

 Linnean Society. I have therefore adopted his name, and omitted 

 that of C. parallelus, which I had conferred upon it. 



Hab. Port St. Julians, S. A. 



-|-j". Elytrorum basi thoracem aequanti. 



6. (7.) C. rotundicollis, Bab. 



Oblongus, thorace elytrorum basin ^quanti, lateribus rotun- 



datis, fuscus, subtus niger ; elytris crebre nigro-reticulatis 



striisque disci punctalis, antennis pedibusque fuscis. (L. c. 



4 ; lat. 2 lin.) 



Whole insect fuscous. Head nearly black on the crown, 



minutely punctured, with two deep foveae between the antennae. 



Thorax transverse, short, broadly emarginale in front, with the 



angles acute, the sides rounded, depressed, rugose, the hinder 



margin sinuated widi a small longiludinal impression on each 



side, the hinder angles rounded ; the anterior margin black, and 



several irregular dark clouds upon the disk. Scutellum dark 



fuscous, with its acute apex paler. Elytra oblong-ovate, so 



thickly covered with dark broad reticulations as to appear nearly 



black, the interior margins paler, the usual striae rather strongly 



marked. Body beneath black. Legs fuscous. 



Hab. Alpine situations in Tierra del Fuego. 



B. Elytrorum apice non truncato, sed rotundato. 

 a. unguiculis anticis magnis. 



7. (8.) C. signatus, Bab. 

 Obovatus, supra fusco-flavicans, subtus niger, vertice nigro, 

 niaculis 2 flavicantibus, thorace macula disci transversa 



