208 ADEPHAGA. [AciliuS. 



The larva of Acilius sulcaius is figured by Schiodtc (ii., PI. iv., Fig. 1), and also by 

 Westwood (Classification, i., p. 100, Fig. 6, 4) : it is elongate, broadest in the middle 

 and strongly narrowed in front and behind ; the head is oblong ovate, longer than 

 broad, and the prothorax is very long, somewhat constricted in the middle and widened 

 towards base ; the remaining segments of the body are short until the seventh, which 

 with the eighth becomes narrowed and cylindrical to apex of the body, which ends in 

 a blunt point from which proceed two short cerci : these are bare, but the sides of 

 the seventh and eight segments are furnished with a thick swimming fringe of 

 cilia ; the colour is yellowish with the head and dorsal scuta rather darker ; the head 

 beai's several dark spots (notal)ly a large triangular one on clypeus), and the hind 

 portions of the segments of thorax and abdomen are fuscous, so that the insect appears 

 banded ; the legs are long, thickly provided throughout with swimming hairs on their 

 upper and under surface, and terminating in'short equal claws. Westwood (1. c. p. 101) 

 observes that "the neck is generally bent downwards and the head turned rather 

 upwards, the parts of the mouth having also the latter direction, so that the animal 

 has the appearance of a small snake : it is extremely insidious in its attacks, the 

 position of the head and neck inducing it to seize objects above rather than in front of 

 it ; so that when an object is perceived floating on the surface of the water the larva 

 rises very cautiously until it has nearly reached it, when, by a sudden jerk of the 

 neck, it seizes the object with its jaws, and immediately drags it under water ; if it 

 still struggle, the larva endeavours to despatch it by repeated jerkiugs of the head. 

 When in the water they may constantly be perceived jerking themselves in every 

 direction, probably for the purpose of seizing upon minute insects." 



1. Posterior femora with base spotted with black .... A. sulcatus, L. 



2. Posterior femora without black markings A. fasciattts, De G. 



A. sulcatus, L. Broad oval, upper surface depressed, elytra 

 broadest behind middle, head and thorax testaceous, the former with 

 two distinct maikings, and vertex, dark, the latter with two transverse 

 black bands across disc which are usually united at the sides by two 

 parallel bands ; elytra fuscous testaceous, sprinkled with very fine and 

 close black markings, side margins light, the whole surface distinctly 

 and closely punctured ; underside black, prosternum and apex of abdo- 

 men testaceous ; sides and margins of abdominal segments marked with 

 yellow ; anterior pairs of legs testaceous ; base of hind femora and hind 

 tibiae and tarsi dark ; antennfe very long and thin, testaceous, with apex 

 of last joints somewhat fuscous ; male with upper surface closely punc- 

 tured and dull, but not sulcate ; elytra of female deeply sulcate almost 

 to apex, thorax with a shallow depression on each side, the sulci and 

 depressions clothed with long yellowish hairs ; the three basal joints of 

 the male tarsi are greatly dilated, and bear one very large cupule and 

 two very small ones. Long. 16, lat. 10 mm. 



Ponds and ditches ; common and widely distributed throughout the kingdom ; the 

 Scotch variety {var. Scoticus, Curtis) has the elytra and sometimes the whole 

 upper surface almost entirely black, and the legs more or less pitchy : it appears to be 

 only a melanic variety, such as is very common among the Scotch Lepidoptera. 



A. fasciatus, De G. (caimlirulafus, Nic). Veiy like the preceding 

 but rather smaller and narrower ; the head is souiewhat differently 

 coloured, the anterior of the black markings being absent ; the black 

 colour is less developed on the ventral segments, and the hind legs are 



