372 
ZOOLOCl ICAL L1TEIIATUIU5. 
Ventral segments free^ five in number^ tlie first visible both at 
the middle and sides ; some of the dorsal segments mem- 
branous. Antenime more or less clavate, but not geniculate. 
Tarsi five-jointed^ in general dilated ; fourth article the smallest^ 
usually very minute. Anterior coxae transverse, not prominent ; 
anterior cotyloid cavities transverse, oblique, more or less open, 
and tapering tovrards the outer side.^^ This diagnosis excludes 
several forms whicli have been referred to the family by various 
authors. Cybocephalus, placed with the Nitidululie by Erichson, 
and continued in that position by Lacordaire, is excluded by 
Murray, partly beeause it does not present the apj)earance of a 
member of this family, but rather resembles Agathidmm^ and 
partly because it exhibits differences in certain important charac- 
ters, especially the structure of the lower surface of the thorax and 
the acetabula of the anterior coxae, and the possession of only four 
joints in the tarsi, instead of five. The relationship of Oyhoct- 
phalus to the Anisotomidae seems to have been strongly impressed 
upon Lacordaire, who refers particularly to the similarity in 
habits, and especially to the possession by Cybocephalus of the 
power of rolling itself up into a ball. 
The Peltidm and Trogositidae differ from the Nitidulidae in 
the structure of the maxillae and tarsi, the former being bilobed, 
the latter having their first joint the smallest. The insects of 
these gToups have already been separated as a distinct family by 
Lacordaire and others. The other group to which the author 
adverts is that of the Rhizophayides, which he regards as inter- 
mediate between Ipides and Trogositidae. Rhizophayus difibrs 
from the true Nitidulidae in having a bilobed maxilla of Tro- 
gositidan structure, and the tarsi less dilated than in the Niti- 
dulidae, and heteromerous (Murray says four-jointed) in the 
males. 
With regard to the geographical distribution of the family, 
Murray remarks (/. c. pp. 228 & 229) that some species are now 
cosmopolitan, but have probably been introduced in many 
places by the intervention of man. Of certain genera, numerous 
species of which occur in some particular region, single species 
are frequently met with in widely distant localities — as, for 
instance, Stelidota, which appears to be an American form, but 
of which one species is known from Tahiti, one from Celebes, 
and two from Madagascar, the last closely allied to North 
American species, and the first to a West-Indian one. Lobiopa, 
an American genus, has one species in Senegal ; Plutychora and 
Perilopa occur both in Africa and Brazil; and Prometopia in 
North and South America, Africa, India, and the Philippine 
Islands. Other genera are scattered in single species almost all 
over the world, and the only extensive genera confined to one 
hemisphere are the American genera Colastus and Camptodes. 
Murray (Linn. Trans, vol. xxiv. p. 230) gives the follow- 
