genera and species of Malacoderm Coleoptera. 395 



to enter upon an explanation or suggestion of the pur- 

 pose or function of any of these developments, but 

 merely to point out the degree in which these seem to 

 have taken place in the Japanese fauna. The inflated 

 form is almost restricted to Africa, but finds its counter- 

 part in the New World ; it is joined to the production of 

 the head into a rostrum. This form is only represented 

 by a single genus, Lycostomus, in the East, and in Japan 

 by but one species. Another form, which seems to me 

 much modified, and to be the one to which the eastern 

 line of development tends, is Metriorhynchus ; this reaches 

 its maximum in Australia, but is represented by but one 

 species in Japan, so far as Mr. Lewis' collections have 

 yet shown ; the rostrum is still present here, but not 

 any degree of inflation of elytra ; but in its place a 

 remarkable modification of thoracic structure takes 

 place, a tendency towards which may be traced through 

 many eastern genera. It is very common throughout 

 the Coleoptera, and, I believe, in other orders of insects, 

 to find a central channel on the disk of the prothorax ; 

 its probable use is explained by the attachment for 

 muscles afforded by the corresponding inward projection; 

 this, therefore, is no peculiarity of the Lycidce, but in 

 fact it gives way to another form, viz., a carina, there 

 being hardly any genus of Lycidce with a simple channel 

 from front to base of the thorax. And the peculiarity of 

 the family consists in this, that not only is the channel 

 converted into a carina, but that various carinae are set 

 up in various directions, reaching a maximum in 

 Metriorhynchus. The most simple form, and that in 

 which we see this change taking place incipiently, is 

 found in a genus Plateros, which in its broad sense is 

 found in all parts of the world, at least where any con- 

 siderable number of the family are found. The channel 

 is present here only at the base of the thorax ; in front 

 a carina is formed. The head is not rostrate ; the 

 antennae are of the simple serricorn type. The elytra 

 have the simplest form of striation, and the nearest 

 approach to true punctuation to be found in the family, 

 not differing so very much from that of the allied 

 families of Elateridce, or from the prototypical forms of 

 Lampyriclce or Telephoridce. This I would regard then 

 as a representative of the undifferentiated type, and it is 

 represented in Mr. Lewis' collections by one or two 

 species which do not depart in any great degree from 

 the North American species of the same genus. 



