216 W. BALDWIN SPENCER. 



state in all, some being well developed in one and some in 

 another respect, but each being degenerate in at least one of 

 the four features. 



Referring to the latter under the numbers (1), (2), (3), and 

 (4), and taking first Hatteria, we find that it shows in (1) 

 and (2) a high, in (3) a low, and in (4) a somewhat low state. 



Varanus giganteus shows in (!) a high, in (2) a con- 

 siderably degenerate, in (3) a high, and in (4) a somewhat low 

 state. 



Calotes shows in (1) a degenerate (i.e. connection with 

 brain lost), in (2) a somewhat degenerate, in (3) a very high, 

 and in (4) a high state of development. 



Chameleo vulgaris shows in (1) a high, in (2) a low, in 

 (3) a fairly high, and in (4) a somewhat low state. 



The same result exactly is obtained when each form is tested 

 in the same way, showing that the organ is never present 

 in a perfectly functional state, but always presents 

 some one feature, at least, in which it is more or less 

 imperfect. 



We are thus brought to the conclusion that the pineal eye 

 in Lacertilia is a rudimentary structure — that at the 

 present time it is not so highly developed as it must have been 

 at some previous period when fully functional. 



It is, indeed, difficult to ascertain whether the structure is 

 now functional at all. In lizards, whose paired eyes are closed, 

 no result is obtained by rapidly focussing a strong beam of 

 light on to the modified eye scale, and thus on to the pineal 

 eye ; in fact, strong light suddenly focussed into one of the 

 paired eyes merely causes the lid to be drawn down without 

 any further apparent result, whilst in the pineal eye there is no 

 protecting lid, and no movement whatever takes place to remove 

 the eye from the direction in which the light is coming. 



Wiedersheim has, since the greater part of this paper was 

 written and the preliminary communication to the Royal 

 Society published, attempted to show that the organ is func- 

 tional and not rudimentary ; he bases his conclusions upon the 

 study of several forms such as Varanus, in which, as pre- 



