66 INSECTA MADERENSIA. 



the more elongated, deeply-coloured, and concolorous ones represented by the 

 T. umbricola, ciistos, alticola, and cautns. It may he readily known from the 

 remainder of the present section by its small size, and by the imiversally testa- 

 ceous margin of its cl}i;ra ; -which is never entirely absent, and which, as though 

 to recognise the same principle of colom-ing which obtains in the last species, is 

 somewhat expanded at the humeral angles and apex, — thus calling to mind in a 

 slight degree the four large and weU-defined patches so conspicuous in that insect. 

 StUl, these spot-like expansions are so doubtful and suffused, compared with those 

 of the T. nigrocvHciatus, that they can scarcely be looked upon as more than mere 

 dilations of the pale marginal Une, — and not therefore as the jiri'^ai'l/ tint of the 

 elytra, left uncovered by the darker central cloud imposed ujion them. And, 

 although it is almost immaterial by which method we choose to consider the present 

 arrangement of the light and dark portions of the surface to have been produced, 

 yet the fact that the former is the most probable is worthy of notice, as showing 

 the maimer in which tlie law of colouring would appear to change at tliis midway 

 point between the two specific extremes. It is essentially a sylvan insect, ranging 

 from al)Out 2000 to nearly 5000 feet above the sea, and aboimding throughout the 

 wooded districts in most parts of the island. I have observed it in great profusion 

 at the Ribeiro Frio, dm-iug the spring and early summer; at the Lombo dos 

 Peccgucu'os, and at the Cruziuhas, in July ; and at the FeijJva de C6rte in August ; 

 and I have like\^'ise captured it in the Boa Ventura in January. It would appear 

 to attain its maxinimn at an altitude of from 3000 to aI)out 4000 feet : and in the 

 upland region of the Fanal it is comparatively scarce, — its place being there 

 supplied by the T. cnstos, which is the prevaiHng species. The var. ji. I have 

 hitherto only taken in the Boa Ventura and at the Cruzinhas. 



49. Trechus dilutus, JVoll. 



T. oblongo-ovatus depressus fusco-piccus, prothorace subcordato basi utrinque profunde impresso 

 angulis posticis acuminato-siibrectis, el\i;ris profunde striatis fusco-testaceis macula postica 

 maxiniA antice valdc suffusa fusco-picca ornatis, antennis iufuscatis, pcdibus pallidis. 



Long. Corp. lin. lj-l§. 



Habitat cum prgecedcnte, sod illo miilto rarior, locos magis editiores pra;cipue colens. 



T. oblong-ovate, depressed, shining, of a dirty piceous-brown, irregularly clouded in parts, giving the 

 surface a somewhat transparent appearance. Prothurax subcordate, or subquadrate and nan-owed 

 behind ; the posterior angles sensibly acuminated, and nearly right angles ; with a dorsal 

 channel ; and a deep fovea on either side at the base. Elytra more deeply striated than in the 

 last species; and with two larger and more distinctly impressed points on the disk of each near 

 the third stria from tlie suture; dull brownish-testaceous, shading off gradually behind into a 

 large cloudy fusco-piceous patch, which is more or less distinct in the different specimens, and 

 which usually covers the entire hinder portion of the surface. Antenna and legs as in the last 

 species, though generally not quite so pale. 



