MUTILLA OF NEW HOLLAND. 21 
DIAMMA, Westw. (In Proceedings of Zool. Soc., April 14, 1835.) 
Corpus elongatum nitidum apterum, thorace in medio constrictum segmentisque abdominis 
basi subcoarctatis. Caput subhorizontale fere rotundatum. Clypeus (fig. 6 a) medio 
longitudinaliter carinatus, antice in lobum transversum, super labrum productus. Labrum 
margine antico ciliato. Mandibule longe curvate falcate, intus et ante apicem acutum 
dentibus tribus aqualibus armate. Maxille (fig. 6b) lobo externo tenui margine 
rotundato ; palpi maxillares graciles 6-articulati articulis 3 et 4 longioribus. Mentum 
corneum (fig. 6c) elongatum labio in apice ejus retractile. Palpi labiales 4-articulati 
articulis intermediis obconicis. Antenne breves convolute 12, articulate articulo 2ndo 
minuto, apicalibus gracilioribus. Thorax quasi binodosus. Nodus anticus fere rotunda- 
tus e collari maximo constans. Mesonotum in annulum brevem angustum contractum. 
Mesosternum majus, obliquum, et pedes intermedios gerens. Metathorax magnus nodum 
posticum thoracis constituens et spiraculis duobus lateralibus instructus. Abdomen 
oblongo-ovale subdepressum segmento basali ad apicem constrictum. Pedes breviusculi 
spinosi unguibus bifidis (fig. 6 d). 
Tue very interesting insect, which is the type of this genus, is 
closely allied to Myrmecodes Latr., or the females of Thynni and 
to Myrmosa Latr. The peculiar toothing of the mandibles, is, 
however, quite unlike that of those insects, whilst the elongated 
maxillary palpi are still more unlike those of the female Thynni, T. 
variabilis 9 for example, in which the maxillary palpi are extremely 
short and apparently only 3-jointed, a peculiarity overlooked by 
Dr. Klug in his Memoir on Thynnus, although it is one which 
would have caused him to hesitate previous to sinking all the genera 
established by M. Guérin. Iam unwillingly prevented at present 
from entering into this part of the subject so fully as it deserves, 
and shall only add that, in the females of Myrmosa, Methoca, and 
Mutilla, the palpi do not differ from those of the males, which is 
also most probably the casein Diamma. The very slight pilosity of 
the body of the type of this genus, its polished surface, articulated 
thorax, and bifid ungues, are all characters which it, however, 
possesses in common with the female Thynni ; which appear to me 
to be its nearest allies. 
Spercies I.—Diamma bicolor, Westw. (Plate 54, fig. 6.)  D. tota purpurea, cyaneo, vel 
zeneo nitens, antennis pedibus mandibulisque rufis, his ad apicem nigris. Long. corp. lin. 
gl, 
Habitat in Terra Van Diemeuii. In Mus. nostr., &. Communic. Dr. Ewing, &c. 
M. Guérin has described a female insect from Kangaroo Island 
(in the Voyage de la Coquille, texte, p. 235,) under the name of 
“* Diamma ephippiger ; Apterus, niger nitidus leevigatus mesothorace, 
metathorace pedibusque fulvis.” Like D. bicolor 9, it has 6-jointed 
maxillary palpi, but the mandibles have only a single tooth within, 
and Mr. Shuckard assures me that this insect is the female of 
Rhagigaster unicolor, an insect which differs considerably from 
Psamatha. 
