Lamellicorn Genus Cryptodus, and its Allies. 25 
of the posterior tarsi; whilst it differs from that genus chiefly in 
the 5-lobed clypeus, transverse labrum, internally toothless man- 
dibles and inner lobe of the maxilla, comparatively smaller 
mentum and more convex body. 
Actinobolus radians. 
Piceo-rufus, antennis tarsisque nigricantibus, nitidus, capitis 
parte postica et pronoto anticé varioloso-punctatis, hujus 
parte postica lined longitudinali media impressa et punc- 
tata, elytris striato-punctatis, in singulo striis 10, tibiis anticis 
extus 4-dentatis, dente infero minuto. 
Long. corp. lin. 9. 
Habitat in Brasilia. 
In Mus. Dom. Hope. 
Trionychus, of Dejean’s Catalogue, is another African genus 
closely allied to Cryptodus, agreeing with it in its depressed form, 
broad head, and large mentum; but in this genus we find the 
mandibles exposed at the sides of the clypeus, as in Phileurus. 
Dr. Burmeister has also separated another group from Phileurus, 
under the name of Trioplus, containing the Ph. cylindricus of 
Mannerheim, and the Ph. sinodendrius of Perty ; these have the 
mandibles 3-dentate, and the anterior ungues dissimilar in the 
sexes, one of them being furnished in the middle with a tooth in 
the males, thus agreeing with Cryptodus. As Dr. Burmeister has 
proposed to illustrate these groups, I shall content myself with 
this short notice of them, which will be sufficient to prove their 
relationship with Cryptodus. 
Directing our attention next to Phileurus itself, we find several 
differences in the form of the mandibles, dependent, as it appears 
to me, on the form of the clypeus. In most species they terminate 
in an acute exposed point, as does also the clypeus, thus forming 
three points in front of the head. The exposed external upper 
margin is elevated (as Latreille expressed it, ‘ latere externo 
eminulo”—Gen. Crust. ii. 103); and this elevated part, where its 
extremity joins the body of the mandible, forms a more and more 
deeply incised notch, thus by degrees forms a separate tooth, In the 
New Holland type of Philewrus,* (Ph. subcostatus, Laporte, Hist. 
Nat. Col, 2, p.116; Ph. depressus, Hope, MSS., which, by the way, 
has greatly the habit of Cryptodus,) we find the front of the head 
* In Mr. Kirby’s Collection, presented to the Entomological Society, is a spe- 
cimen of a Philewrus marked as from New Holland, and, as received from Mr. 
Mac Leay, with the pin stuck through the thorax very low, which appears to me 
to differ in no respect from Ph. valgus. 
