176 



HARD WICKE'S SCIENCE- G OSSIF. 



be decidedly slow. The late Rev. Lansdowne 

 Guilding, who held the office of colonial chaplain at 

 St. Vincent's, has described a new genus of the sun- 

 fish tribe, which has been named Pedalion gigas. 

 Guilding first observed the remarkable characters in 

 the eye of the sunfish, its construction being conical 

 and versatile, enabling the fish to look different ways 

 at one time, or have an exceedingly wide range of 

 view." Mr. Andrews further remarks that Ortha- 

 goriscus is related to the Syngnathidae or Pipe-fishes 

 by the versatile structural arrangement of the eyes ; 

 and by several authorities it is stated that the eyes of 

 Hippocampus move independently of each other, as 

 in the Chameleon, the eyes of which " are remarkable 

 objects, large, projecting, and almost entirely covered 

 with the shagreen-like skins, with the exception of a 

 small aperture opposite to the pupil ; their motions 

 are completely independent of each other: It adds to 

 the strange and grotesque appearance of this creature, 



Fig. loi.— Orthagoriscus Mola. 



to see it roll one of its eyeglobes backwards, while 

 the other is directed forwards, as if making two 

 distinct surveys at one time." 



Now I venture to suggest, and so far as I know the 

 suggestion is original, that this versatile motion of 

 the eyes of Orthagoriscus does probably depend very 

 much on the watery fluid with which the eyeball is 

 surrounded, and that perhaps the like versatility in the 

 Pipe-fishes and Chameleon may depend on a similar 

 cause. 



The late Dr. Jacob of Dublin published a paper on 

 the anatomy ol Orthagoriscus Mola in the "Dublin 

 Philosophical Journal," to which I have not access. 

 It would be very strange if he could overlook the 

 fluid existing in the orbit. Dr. Cobbold (" Intellec- 

 tual Observer," vol. ii. p. 85) states that in the year 

 1856 a large specimen was anatomised by the 

 Professor of Anatomy in the University of Edinburgh, 

 but who he was, or whether he published his observa- 

 tions, I do not know. Dr. Bellingham, a skilful and 



devoted anatomist, published in the "Dublin Maga- 

 zine of Natural History," 1840, a description of a 

 specimen he had dissected : his reference to the eye 

 is as follows : " The aperture of the eye is somewhat 

 oval, 2\ inches by 2 inches in the long diameter from 

 before, backwards ; the eyes have a deep blue 

 colour ; the iris silvery white, \ inch wide ; when 

 the eyeball was pressed inwards, a white membrane, 

 resembling the meiiibrana nictitans appeared and 

 could be made completely to cover the eye." INIy 

 observation was that there was no viemhrana nictitans, 

 nor anything resembling it, but that when the eye- 

 ball was pressed inwards the membrane closing the 

 orbit, becoming corrugated, folded over the cornea 

 and was capable of quite concealing it. 



A few words about Cccrops Latreillii, a parasitic 

 Crustacean found on the gills of Orthagoriscus Mola. 

 I took nearly thirty specimens from the gills, and to 

 remove thick adherent slime placed them for a short 

 time in weak solution of potash. They were after- 

 wards washed in several changes of fresh water, 

 and left immersed, supposed to be dead. On 

 inspection after a few hours all the females had 

 become very much enlarged posteriorly, the ova (I 

 suppose) having absorbed some portion of the alkaline 

 fluid, and in nearly every case a male was found 

 attached to each, legs to legs as in mutual grasp. I 

 separated some with a fine pointed forceps and exa- 

 mined them individually. What necessity, instinct, 

 stimulus or attraction, under such unfavourable 

 circumstances, caused the union of these moribund 

 parasites, I cannot attempt to conjecture. 



J. W. BUSTEED. 

 Castle Gregory. 



A STUDY OF THE VARIATION OF THE 

 SMALL TORTOISESHELL BUTTERFLY 

 (VAJ\r£SSA URTICjE). 



By A. H. SwiNTON. 



Part XL 



\Continued /roTtt page 149.] 



AS butterflies sometimes mate with species that 

 are not in any way allied, and butterflies even 

 pair with moths, we might hereupon conjecture with 

 a shudder that such jackdaws in peacock's feathers 

 might have something in common with minotaurs, 

 mules, and angels. But as it is, we recognise a much 

 more general and widespread agency insensibly 

 working on European areas, originating in the re- 

 tardation and acceleration of metamorphosis ; and 

 this when caused by change of climate or season we 

 know gives rise to varieties and races. In the 

 present instance I may quote the case of the 

 black tortoiseshells. As the story goes, one day 

 about the year 1858, a friend called on a certain 

 entomologist with a box of small tortoiseshell butter- 



