52 the president's address. 



the Hypopial Nymph of the Dermacarus of the squirrel, and of the 

 closely-allied form found on the mole, chitinous labia for the same 

 purpose are developed round a concave furrow at the extreme 

 hinder-end of the ventral surface. 



After this most important of all arguments on the subject I may 

 refer to other points which, if they have not the far-extended 

 range, are possibly more striking to many minds ; such a feature is 

 the existence of rudimentary organs in some species or forms which 

 are useless and functionless in them, but are effective in allied 

 creatures. Thus the eyes of Spalax and Chrysochloris among 

 Mammals, and of Myxine amongst fishes, are hidden beneath the 

 skin and incapable of receiving luminous impressions, and in the 

 young of Petromyzon they are actually covered by muscles. Again, 

 the whales have a rudimentary pelvis and hind limbs hidden 

 beneath the skin, and among snakes the boa-constrictor has rudi- 

 mentary hind limbs quite unserviceable. In snakes generally one 

 lobe of the lungs is rudimentary. In Apteryx the minute wing is 

 hidden by the long hair-like body feathers. The Chalcididce and 

 allied families are very interesting in this respect, as even in the 

 British species we may find almost every stage, from the possession 

 of four powerful wings hooked together in pairs, as in most other 

 Hymenoptera, to an entirely apterous creature. In some all four 

 wings are reduced in size, and this is found in endless grades in 

 different species. In Mymar the hind-wing is abortive except the 

 costal nervure, which is shortened, but persists and is attached to 

 the slender fore-wing by a single hook, forming a supporting piece ; 

 while in other forms only the nervure exists in all four wings ; and 

 lastly we find forms where even this is absent. Again, the repro- 

 ductive organs are instructive. It is difficult, except by descent, to 

 accouut for the functionless mammae of the male in man, or for 

 the so-called uterus masculinus, really the homologue of the 

 Mullerian ducts (or oviducts), of the female ; while, on the other 

 hand, in rodents, moles, and lemurs, the clitoris is actually per- 

 forated by the urethra, a singular confirmation of the received view 

 as to the morphology of this organ. Probably, however, one of 

 the best instances is the late discovery of a third central eye, use- 

 less and hidden beneath the skin, in some lizards ; and the connec- 

 tion of this eye with the so-called pineal gland found in mammals 

 and even in man himself, which is a small projection of the brain 

 the use or origin of which has puzzled anatomists to no small 



