18 Rev. H. Clark on the Dytiscidee 
Genus 3. Acasus, Leach (Zool. Mise. iii. p. 69). 
1. A. latissimus, n. sp. 
A, ovalis, subcircularis, valde latus, depressus, punctato-striatus, niger, 
nitidus; capite subtilissime punctato, ad basin rufo bimaculato (aut 
forsan aliquando rufo marginato); thorace antice excavato, ad latera 
antice compresso, rotundato, tenuiter marginato, angulis posticis acutis, 
subtiliter punctatulo, nigro, lateribus et angulis anticis rufo-fuscis ; 
scutello lato, nigro; elytris latis, breyibus, depressis, subtilissime punc- 
tatis, punctorum seriebus duabus obsoletorum; corpore subtus plano, 
haud convexiusculo, rufo-fusco; abdominis segmentis ad latera rufo 
notatis; pedibus antennisque rufo-fuscis. 
Long. corp. 3} lin., lat. 21 lin. 
A very aberrant form of the genus Agabus. Examples are in the 
cabinet of the British Museum, labelled ‘“‘ New Holland.” 
2. A. spilopterus, Germ. (Linn. Ent. 1848, p. 172). 
Corresponds in size to Agabus uliginosus, but, according to the 
examples before me, varies somewhat in length and comparative 
breadth of body. It may be recognized by three flavous markings 
on the head, and a narrow flavous line near the central margin of 
the elytra; in some examples two minute circular flavous spots may 
be discerned near the inner side of this flavous line. 
I am indebted to Dr. Schaum for a typical example of this species 
from the cabinet of Germar. In the collections also of the British 
Museum, Mr. Bowring, and Mr. Waterhouse. 
3. A. Tasmanic, n. sp. 
A. breviter ovatus, latus, sat depressus, obscure punctato-striatus, sub- 
tilissime vermiculatus, niger, nitidus ; capite inter oculos undique bi- 
punctato, nigro, ad apicem rufo; thorace antice emarginato, ad latera 
rotundato et leviter marginato, basi sinuato; elytris punctorum seriebus 
tribus obscuris ; pedibus rufo-fuscis, antennis flavo-rufis, corpore subtus 
nigyro. 
Long. corp. 38-34 lin., lat. 13 lin. 
A. Tasmanie is smaller and narrower than A. latissimus; it is 
much more levigate than, and without the fuscous markings of, A. 
reticulosus ; it is notso constricted in form as A. lugubris, Homb. ; it 
approaches most nearly to A. spilopterus; it is however smaller, the 
head has no medial rufous markings, and the rows of punctures on 
the elytra differ somewhat as to their position, and consist of single 
punctures evenly arranged in line, not irregularly disposed. Two 
examples of this species have been received by Mr. Bakewell from 
Tasmania. 
