1899] B RE VIS ESSE LABORO, OBSCURUS FIO 87 



The preceding remarks were prompted by a paper entitled "A 

 Hunt for a Name," contributed by T. S. Hall to the Victorian Naturalist 

 for May, 1899. The difficulties to which we have alluded are of 

 course magnified in outlying parts of the world, where fellow-workers 

 are few. In trying to name a coral, Mr. Hall found himself referred 

 by the reporter of the Challenger to " Plesiastraea urvillei, Milne- 

 Edwards and Haine, Cor. II., p. 490." On this "almost meaningless 

 reference " Mr. Hall remarks : " When one knows the country it is 

 easy for him to find his way about, but to the stranger it is not easy, 

 and he needs the finger-posts which the other never heeds. ' Cor. II.' 

 is good enough for the specialist, but is a meaningless ' blaze ' for the 

 ' new chum.' ' We are glad that Mr. Hall refused to regard " Cor. II." 

 as a Biblical reference, and that he eventually discovered " Histoire 

 Naturelle des Coralliaires " ; but what language would he have used 

 had the Challenger reporter followed the custom of his kind, and con- 

 tented himself with " P. urvillei, E. & H., Cor. II." ? 



The Parietal Eye. 



The parietal eye and adjacent organs of the New Zealand Tuatera 

 (Sphe7iodon) form the subject of an important paper by Mr. A. Dendy 

 in the May issue of the Quart. Journ. Micr. Soc. It has already been 

 shown that in the adult of this reptile this eye is better preserved than 

 in other animals ; and the author now demonstrates that its develop- 

 ment has undergone less modification than in other reptiles. The first 

 indication of its appearance is seen at a stage (K) comparable with a 

 two-day-old chick, when a " primary parietal vesicle " buds on the roof 

 of the fore-brain slightly to the left of the median line. At stage N 

 the eye forms a hollow vesicle in front and slightly to the left of its 

 so-called "stalk" — the "parietal stalk," which is a finger-shaped 

 diverticulum of the root of the fore-brain, practically in the middle 

 line. The eye is almost or completely separated from the stalk, which 

 contains a prolongation of the cavity of the brain. The " paraphysis " 

 likewise makes its appearance at this stage, as a backwardly-directed 

 outgrowth of the roof of the fore-brain. 



At stage the parietal eye and stalk are conspicuous externally ; 

 while at stage B (the one immediately before hatching) the eye, which 

 is now apparently median, is seen as a white spot with a black border, 

 the latter representing the pigmented margin of the retina and the 

 former the lens. In the adult (stage S) the eye, though very highly 

 organised, is no longer recognisable externally ; but in recently hatched 

 individuals it is stated to be still visible as a dark spot through the 

 translucent skin covering the parietal foramen. 



After discussing the structure of the eye and its nerve, and the 



