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XV. On some unusual monsti'ous Insects. By J. 0. 

 Westwood, M.A., F.L.S., &c. 



[Read June 4th, 1879.] 



(Plates VI. and VII.) 



A. Insects avith extra development of Wings. 



In tliG various classifications of monstrous or abnormal 

 productions of Nature which have been proposed by phy- 

 siologists, a large and important division has comprised 

 those individuals which possessed more than the oixlinary 

 structures of the type of the species. To such individuals 

 the name of " Monstra per excessum " has been applied. 

 By M. Lacordaire they were termed " Monstres poly- 

 mcliens," fi'om which the term of Polymelianism may be 

 applied, to distinguish this form of monstrosity. Among 

 the articulated animals (to which the name oi Arthropoda 

 is now applied) this kind of monstrosity is of compara- 

 tively moderate extent. In fact, no specimen has hitherto 

 been described in which more than a single head or a 

 single body has been found in the individual monster, the 

 monstrosity being confined to an extra number of legs and 

 antennaa, or joints of those organs. Of both of these ab- 

 normities the number of instances has been considerable, 

 but additional wings or portions of wings are of such rare 

 occurrence that no such instance is recorded by Lacor- 

 daire or other writers on Entomology.* 



From this circumstance it may be inferred that there is 

 a greater analogy between the legs and antennre of an 



* M. Isidore Geoffroy Saint Ililaire divides Polymelian monsters into 

 five genera: 1, Pygomelians (where the additional members are affixed to 

 the pelvic region) ;f 2, GastromhUant; (to the belly); 3, Notomellans (to 

 the back); 4, Ce])halomel%ans (to the head), and Melomilians (to the 

 other members). "Tons les cas observes jusqu'a ce jour, parmi les 

 insectes appartiennent a la Melomt'lie et Ton en connait dejii un assez 

 grand nombre, (pii tons portent sur les anteiuics et lesj^aites." Lacordaire, 

 Introduction ii. p. 444. 



t M. Lacordaire considers the statement of Paullin, " Epliemcr. des Curieux de la Nature," 

 Dec. iii. Ann. iii. p. 316, that he had observed a fly which had a third wiug implanted on 

 the podex, as unworthy of credit. 



TRANS. ENT. SOC. 1879, — PART IIL (dEC.) R 



