7s 



Tribe Ptiliina. 



Gen. XVII.— PTILIUM. 



The thirteen species now added to this <jenus comprise representatives of 

 all the existing groups : P. Simsoni is allied to the beautiful I'. Halidaii and 

 P. angidicolle ; I'. Hornianum to /'. Kunzei; I' incog nitum and P. fissicolle belong 



to the group which oxhihit longitudinal lines on the thorax, as P. < .ninttiim .• the 

 remaining species, with one exception, may be referred to the group of which 

 /'. Spencei is the most common exponent, The exception I allude to exists in 

 /'. obccECatum ; in this we meet with a very abnormal form, differing from all the 

 other species both in general appearance, and in the almost total absence of eyes. 

 It is represented by a single individual in the collection of Herr E. Reitter ; and, 

 since on that account dissection was unattainable, 1 have placed it in this somewhat 

 heterogeneous genus. 



I call Ptilium a heterogeneous genus on account of the dissimilarity of its 

 component groups, but at the same time 1 cannot clearlj si e how these groups can 

 be accurately defined as separate genera. Col. Motschulsky made an attempt to 

 do this, and 1 would gladly adopt his divisions, if definition was possible. Let us 

 take as an example the genus Ptiliola, originally named by Prof Haldeman. 

 Motschulsky mentions /'. Kunzei as the type of Ptiliola, and could the genus be 

 restricted to that species and P. Collani it would be sufficiently distinct ; but it 

 must also include P. S]>cnc<i with its numerous allies, many of which more closely 

 resemble P. exaratum, and those with longitudinal lines on the thorax. And 

 similar ambiguity exists even more palpably in some of his other divisions. On 

 the whole 1 think that species whose affinities are so widely distributed and so 

 closely interlaced should be comprised under a single genus, rather than divided 

 into various indefinite genera. 



The foregoing remarks were written a long time before I had seen Dr. Flach's 

 'Essay,' which I have noticed in the preface; and I do not consider it worth while 

 to alter them to any great extent, as they still express my own ideas. As far as 

 the genus Ptilium is concerned, Dr. Flach has, in the 'Essay' referred to, followed 

 the lines laid down by Col. Motschulsky in the Etud. Ent. iv. p. 17, 1855, but has 

 substituted fresh names for many of those originally given by that author, and has 

 added some new genera for species which he had himself first described. Among 

 the latter he created the genus Typhloptilium to contain an insect which he had 



iously described in the Deuts. Ent. Zeits. 18)Sf), p. '218, under the name of 

 Ptilium OEdipus. J Jut 1 do not perceive that this specie.- presents any characters 

 sufficient to justify generic separation. The absence of eyes cannot of itself be 

 considered conclusive, for in the well-known genus Ptinella this is merely a sexual 

 distinction and exists only in certain species. And, moreover, in J'. CEdipus 

 minute eyes possessing visual facets can be discovered by close investigation. 1 ani 

 speaking now of my own specimen; it is quite possible that others may be found 

 in which the eyes are totally absent. Nevertheless, some more obvious anatomical 

 character would be required to constitute a new genus. But, under any circum- 

 stances, the name < l'.ilit>tt>, by which this insect was described by Dr. Flach in 

 1886, must be retained for the species. 



