THE TRIMORPHISM OF PYRRHOSOMA NYMPHULA. 179 
bifureation of the median line, but there is no connection with 
the circlet at the apical suture. Segments three and four are 
often similar to number two, but when, as sometimes happens, 
the median line is continued through the bifurcation to the 
circlet, an anchor-shaped spot is produced, the stock of the 
anchor being represented by the circlet. Segments one and five 
to ten appear to be normal and constant. 
The legs of Stephens’s specimen are, as stated in the descrip- 
tion, tawny-red, and so are the legs of a more mature example 
of the same form taken at Folkestone by Mr. O. Thomas on 
May 15th, 1892, also in the Museum; but in all the other speci- 
mens which we have seen the legs are black, as in the teneral and 
adult states of normal males and females. 
This form is quite common. An example from Folkestone 
has been already mentioned, as well as two Surrey localities 
given by Stephens. Mr. W. J. Lucas has shown us a specimen 
bred from a Surrey nymph in May, 1900, and another taken on 
Esher Common on June 10th of the same year. We have the 
form from Epping Forest (June 16th, 1907; June 14th, 1908 ; 
and May 9th, 16th, and 30th, 1909). The British Museum pos- 
sesses a specimen from De Selys’ Collection, and another from 
Germany presented by Mr. W. F. Kirby, and collected during 
July, 1887. 
Var. melanotum (De Selys). 
This uncommon form has been excellently figured by Mr. 
W. J. Lucas (Entom. 1901, pl. i. fig. 8), and more recently Mr. 
K. J. Morton has restored to it its Selysian name, which had 
been overlooked (ibid. 1908, p. 388). We observe from Mr. 
Lucas’s paper on the Dale Collection (Ent. Mo. Mag. 1909, p. 82) 
that that collection contains at least one specimen of melanotum. 
Another example is in the Stephens Cabinet; it carries the 
usual oval ticket, and a printed label reading ‘‘ Lincolniense 
Step.” It is probable that De Selys saw this insect when he 
consulted the Stephens Cabinet in 1845, for the following entry 
appears in the synonymy of Agrion minium given in his ‘ Re- 
vision of the British Libellulide,’ published in the following 
year :—‘‘ A. lincolniense, Steph. Catal. and Ill. (partim: the 
young female).”’ The courtesy of Mr. Lucas has enabled us to 
compare with Stephens’s specimen an example of eneatum taken 
in the New Forest on June 5th, 1900, with the result that the 
comparison has established complete agreement. 
Agrion lincolniensis is set out in Stephens’s ‘ Catalogue’ as a 
separate species, thus: ‘‘3418. 9, Lincolniensis. Dale MSS.” 
As no description is given, of course the bare name cannot stand. 
Afterwards, in his ‘ Illustrations,’ Stephens wrongly identified 
this distinct insect with Agrion chloridion (Charp.), and sunk the 
name lincolniense as a synonym of that species. But it is clear 
that the dragonfly to which Charpentier gave the name chloridion 
