40 



I would make here a distinction that is of some importance ; an 

 interference or injury that affects the germ-plasm and makes it 

 develop abnormally produces a monstrosity, but if it only prevents 

 it at some late stage or other from completing its development, the 

 result is not usually regarded as a monstrosity. For instance, the 

 deformed feet of Chinese ladies are hardly to be called teratological, 

 nor the oblique skulls which some tribes do, or used to, produce by 

 pressure. 



Similarly, to come to our Lepidoptera, a leg with two tarsi is 

 teratological, but a wing misshapen, or with a hole in it, or wanting a 

 portion, due to some mechanical interference with the pupa, is 

 strictly not teratological. 



Of course, when we come to an actual specimen, unless we know 

 more of its history than we usually do, it is only possible to say 

 tentatively that the deformity of wing is the result of intrinsically 

 abnormal development ; or, on the other hand, of some interference 

 with development. 



We must, however, admit that this way of looking at the matter is 

 really a question of where we are to draw the line. If many genuine 

 teratological examples are due to mechanical (or other) interference 

 at an early embryonic stage, do the results of such interference cease 

 to be teratological at a later stage ? and when ? A butterfly breaks 

 its wings : we do not regard the result as teratological. After emerging 

 from the pupa it fails to expand them properly: we call it a "cripple " 

 and not a teratological specimen. Perhaps the line should be drawn 

 here, but I incline to go one stage further back, and regard damage 

 to the wings after the moult to pupa as being simply an injury and 

 not teratological. 



In the Vertebrata no small proportion of monstrosities described 

 belong to the class of double monsters, /. e. there is one individual, 

 with the whole or some portion of another attached to it, by a bifur- 

 cation of the vertebral axis, or in some other way, a malformation 

 dating from the very earliest trace of the embryo on the germinal 

 layer in the ovum. A consideration of these need not detain us, for 

 the only record of such a malformation in insects I have met with 

 is of a Chironcmus larva with two heads, but with the segments 

 behind uniting, so that from the third abdominal segment backwards 

 there is only one body ("Stett. Zeit.," 1873, p. 452). 



Of insect monsters that unquestionably date from the earliest 

 embryonic period, I know of very few. One of the most remarkable 

 of these was the specimen of Afithidiitm manicatum^ described in 

 "Proc. Ent. Soc. Lond.," 1907, p. Ixi, by the Rev. F. D. Morice, in 

 which, in the closing of the visceral cavity, the ends of opposite sides 

 of the segments did not meet their fellows, but joined the next in 

 order, so that the abdomen is not segmented, strictly speaking, but 

 the plates form a continuous spiral from the third abdominal 

 segment to the last. 



In the Natural History Museum are two or three Hymenoptera 



