350 Mr. Newport on the Class Myriapoda, Order Chilopoda. 



of a small number of segments, covered by only eight dorsal plates, each of 

 which covers two ventral segments. These characters distinguish the Cer- 

 matiidce from other Myriapoda, and are uniform in all the species. This great 

 similarity of structure renders the identification of the species exceedingly 

 difficult, the consequence of which has been, that naturalists have fallen into 

 the error of assigning to particular species characters that are common to the 

 genus. Thus, Fabricius has assigned to his species C. longicomis the number 

 and scutellate form of the dorsal plates, with rounded margins, and median 

 stomata; and elongated legs and antennae; all which are common to the 

 whole family. Mr. Templeton also has recently fallen into a like error in 

 employing the minute spines on the edges of the plates for the same purpose. 

 Indeed so similar is the structure of the different parts of the body in all the 

 species, and so alike are the colours and markings on the body and limbs, 

 that it is not to be wondered at that so few species have hitherto been recog- 

 nised. Thus, I have never yet seen a species of Cermatia in which the legs 

 were not more or less annulated with dark fasciae, or which had not longitu- 

 dinal bands of colour on the dorsal plates. Yet the colour and markings of 

 the body, when carefully examined, are usually the most obvious indications 

 of the species. When specimens are preserved in a dry state, their colours 

 do not undergo much change, but remain tolerably perfect, and may then be 

 relied on as some of the best characters. But when any Myriapoda have been 

 long preserved in spirit, it is almost impossible to make out even the markings 

 with much certainty, as the original colours disappear, and very little more than 

 the former existence of coloured fasciae, or even of the annulations on the legs, 

 can then be distinguished. The only anatomical characters on which we can 

 rely with certainty in the Cermatiidce are derived from minute variations in 

 the form, and the relative lengths and dimensions of the different structures. 

 Mr. Templeton* has lately employed the relative length of the antennae and 

 legs to that of the body, and the size of the spines on the edges of the dorsal 

 plates, as good marks of species. But excellent as are the first of these cha- 

 racters, and although they are almost invariable in uninjured specimens, they 

 require to be taken in conjunction with other peculiarities, since the antennae 

 are very frequently injured, and the posterior legs, which easily fall off, may 

 * Transactions of the Entomological Society of London, vol. iii. part 4, 1843. 



