26 MADEIRAN COLEOPTERA. 
77. Hydroporus Lyellii, n. sp. 
H. oblongo-ovalis tenuiter pubescens, supra pallide testaceus, infra 
niger, prothorace ad latera oblique subrecto, postice angustissime 
nigro-marginato necnon macula sat magn& submedia (marginem 
nigrum attingente) utrinque notato, angulis posticis acutis, elytro 
singulo lineis quinque latissimis nigris valde confluentibus ornato. 
Long. corp. lin, 2-21, 
H. oblong-oval (being a little less straightened about the middle 
than the preceding species), and clothed with an exceedingly 
minute, whitish pubescence; above pale-testaceous, below black. 
Head dusky along its hinder region. Prothorax rather short ; 
and nearly straight (though oblique) at the sides, being broadest 
behind,—where its angles are acute; with a few large but shallow 
punctures towards its anterior and posterior margins,—the latter 
of which is always, and the former sometimes, narrowly edged 
with black; with a tolerably large and well-defined patch on 
either side of the hinder disk, and confluent with the darkened 
posterior margin, likewise black. Hlytra with the suture, and five 
very wide longitudinal lines on each, more or less confluent, and 
sometimes covering nearly the entire surface, black,—leaving, how- 
ever, the apex and outer margin, and a space on each contiguous 
with the latter (and a little before the middle), more broadly 
testaceous, or free from markings, than any other portion of the 
surface. 
The present Hydroporus was discovered by myself, in a brackish 
stream towards the north of Porto Santo, during April of 1855, It 
is clearly the representative of the H. Ceresyi of Mediterranean lati- 
tudes,—if indeed it be not, in reality (of which I am by no means 
convinced), the selfsame species altered by the local influences to 
which it has been so long exposed. Since Dr. Schaum, however, of 
Berlin, to whom I submitted it for examination, regards it as distinct, 
and since it does certainly possess many features of its own (whether 
natural or acquired) by which it may be instantly recognized from its 
ally, I have retained it as such,—dedicating it to Sir Charles Lyell, 
whose researches in Madeira have thrown so much light on the geo- 
logy of those islands. It may be at once known from the H. Ceresyi 
by its rather smaller size and more darkened surface,—both its pro- 
thoracic patches and elytral lines being much more developed than 
those of that insect. The former indeed, which are exceedingly 
minute in the European species, are here of a considerable size, and 
confluent with the hinder darkened margin; whilst the latter are 
increased to such an extent as to run into each other, and almost to 
cover the entire surface. From the Madeiran H. vigilans its di- 
minished bulk and minutely pubescent body, in conjunction with 
