146 RICHARD EVANS. 



after perusal of the facts which will be recorded in the coming- 

 pages, that Peripatus guianensis is a new species. 



Perhaps, before proceeding to the actual description, it 

 would not be out of place to refer to the utter uselessness of 

 much that has been written on the Peripatidag, especially 

 as regards the colour and dimensions of preserved specimens. 

 In the first place, observations made on the colour of speci- 

 mens preserved in either alcohol or formalin have little or 

 no value. The colouring matter existing in the skin of 

 the neotropical Peripatid^e is gradually abstracted by the 

 above-mentioned reagents, and the characteristic markings 

 and patterns, when such exist, disappear in a few days. 

 Ultimately the animal becomes quite colourless, the colouring- 

 matter being dissolved in the preserving liquid, and giving it 

 a more or less brownish tint. Unfortunately this is only too 

 true of P. guianensis, which is the subject of the present 

 paper. After the specimens had been in either spirit or 

 formalin for a few days the characteristic markings had 

 disappeared so completely that no one would have suspected 

 the presence of two distinct species among the specimens in 

 my possession, unless he took into consideration some character 

 other than the coloration, although in the living animal the 

 distinctive markings of P. guianensis were so evident that 

 the black man who collected the specimens for me Avas able 

 at a glance to separate the individuals belonging to this 

 species from those of the other species found in Demerara. 

 In consequence, I have been forced to the conclusion that 

 observations made on the coloration of neotropical forms of 

 the Peripatidfe, to be of any value, must be made on the 

 living animal. 



In the second place it is fashionable, in describing a new 

 species or in redescribing an old one, to give the exact dimen- 

 sions of the specimens. The length, depth, and width of the 

 animal are carefully recorded, and very often tabulated ; the 

 length of the antenna) and the distance between the succes- 

 sive pairs of legs are observed with great care, but all to no 

 purpose, save to show that the author is capable of paying 



