THE TRIMORPHISM OF PYRRHOSOMA NYMPHULA. 179 



bifurcation 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. 0. 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 weil 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 ]\ray 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, pi. i. fig. 3), and more recently Mr. 

 K. J. Morton has restored to it its Selysian name, which had 

 been overlooked {ibid. 1908, p. 38). 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 

 StejJ." It is probable that De Selys saw this insect w^ien he 

 consulted the Stephens Cabinet in 1845, for the following entry 

 appears in the synonymy of Agrion minium given in his ' Ee- 

 vision of the British Libellulidse,' published in the following 

 year: — "A. lincolniense, Steph. Catal. and 111. (partim : the 

 young female)." The courtesy of Mr. Lucas has enabled us to 

 compare with Stephens's specimen an example of (sneatum 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, LincolnieDsis, Dale MS S." 

 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 synon3'm of that species. But it is clear 

 that the dragonfly to which Charpentier gave the name chloridion 



