208 



KNOWLEDGE. 



[September 2, 1895. 



five well-defined stars of loth to IGth magnitude, that 

 may or not be physically connected with the nebula. 



ELLIPTICAL NEBULA M. G5 LEONIS. 



E. A. llh. Ibm. 423., Decl. North 13° 38'. 



Scale, 1 millimetre to 12 seconds of arc. 



The photograph was taken with the 20- inch reitector on 

 February 28fch, 1894, between sidereal time Sh. 19m. and 

 12h. 2m., with an exposure of the plate during three hours 

 and forty minutes. 



References. ' 



N. G. C. No. 3623, G. C. No. 2373, h 8.54. 



Sir -T. Herschel {G. C. 2373) describes the nebula as 

 bright, very large, much extended in the direction l(i.5 ±, 

 gradually brighter in the middle, with a bright nucleus ; 

 eight observations were made. In the F/iil. 'J'lans. for 

 1833, PI. XIV., Fig. 53, he gives a drawing, but it does 

 not compare well with the photograph. 



Lord Eosse {P/til. Tram. 1850, PI. XXXVII., Fig. 7) 

 gives a drawing of the nebula, and on p. 512 states that it 

 is resolvable, a spiral or an annular arrangement about it, 

 no other portion of the nebula resolved; and in the ohs. 

 of Xt'l). and CI. of Stars, p. 95, he gives the results of eight 

 observations made between the years 1849 and 1861, and 

 states that he suspected seeing at times dark spaces on 

 either side of the nucleus, and some mottling and stars 

 sparkling in it. He also saw a star close fotl'winij the 

 nucleus, but did not see the curious rmg which he says 

 Sir .J. Herschel saw. 



Lassell [Uem. U. A. S., Vol. XXXV., p. 43, and PI. III., 

 Fig. 15) describes the nebula as faint, irregular, formless, 

 and suspected that he saw some stars in it. The drawing 

 does not resemble the photograph. 



The photograph shows the nebula to be a symmetrical 

 ellipse with a well-defined stellar nucleus surrounded by 

 dense nebulosity, in the midst of which is a spiral ring filled 

 with nebulosity ; and this, together with the nuclear 

 condensations, is surrounded by two elliptical rings of 

 nebulosity, separated by a dark space. Five star-like 

 condensations of nebulosity are involved in the rings, and 

 one bright star is in the dark space between them, on the 

 south foUon-inij side of the nucleus. The nebula as a whole 

 is more perfectly symmetrical than the Great Nebula in 

 Andromeda, of which class it is clearly a type ; but I have 

 not before seen on any of my photographs a spiral with a 

 stellar nucleus, involved in the dense central nebulosity. 



SPIRAL NEBULA M. 66 LEONIS. 



E.A. llh. 15m. Is., DecL North 13° 32'. 



Scale, 1 millimetre to 12 seconds of arc. 



The photograph was taken with the 20-inch reflector on 

 February 28th, 1894, between sidereal time 8h. 10m. and 

 12h. 2m., with an exposure of the plate during three hours 

 and forty minutes. 



Eeferences. 



N. G. C. No. 3627, G. C. No. 2377, h 857 = 875. 



Sir J. Herschel {G.C. 2377) describes the nebula as 

 bright, very large, much extended in the direction 150^, 

 much brighter in the middle, two stars w. p. ; nine observa- 

 tions made. In the Phil. Trans. 1833, PI. XIV. Fig. 54, 

 a drawing of it is given which, in outline, resembles the 

 photograph, but the extension is in the direction of about 

 180°. 



Lord Eosse {Obs. of Neb. and CI. of Stars, p. 95) describes 

 it as a spiral, well resolved about the nucleus, but in no 

 other part, two stars involved in it, with others and knots 

 of nebulosity suspected ; could not resolve the nucleus. A 

 marginal sketch is given and a drawing in the Phil. Trans. 



1861, PI. XXVII., Fig. 16, where some spirals are shown, 

 but the resemblance to the photograph is not evident. 

 Eleven observations were made between the years 1848 

 and 1857. 



The photograph shows the nebula to be an imperfect 

 spiral with a well-defined stellar nucleus which forms the 

 pole of the convolutions, involved in which I counted four- 

 teen nebulous star-like condensations. We see in this 

 nebula much that is suggestive of a transition state into 

 the more perfect form of spiral. 



It should be understood that my remarks concerning the 

 four nebula? which have been referred to are based upon 

 the examination of the original photo-negatives, and that 

 many faint details are visible upon them which cannot be 

 fully reproduced upon the paper prints. 



Note. — Eeferring to the area of the sky represented by the 

 photograph containing the Cluster and Nebula in Aniils, 

 in the last number of Knowledge, it should be between 

 R.A. 7h. 34m. 403. and R.A. 7h. 39m. 403. ; DecL, 

 between 13° 46' and 15° 21' South, instead of the 

 co-ordinates giveu in the letterpress. 



BLIND CAVE-ANIMALS. 



By R. Lydekker, B.A.Cantab., F.E.S. 



I READ the other day, in an American scientific 

 journal, how that a labourer, while digging a well 

 in Orange County, at a depth of about thirty feet 

 below the surface, struck a subterranean rivulet, and 

 that with the water from the same were brought up 

 to the daylight several blind and colourless crayfish, which 

 proved to belong to an unknown type. This led me to 

 think that the readers of Knowledge might be interested 

 to learn something regarding the large assemblage of blind 

 animals of various kinds which inhabit caves and sub- 

 terranean waters in different parts of the world. 



True cave-animals, that is, those which are blind and 

 more or less completely colourless, and spend their whole 

 time in utter darkness, must be sharply distinguished from 

 creatures like bats and owls, which take advantage of 

 such situations as a temporary shelter, from which they 

 issue forth at night to the outer world. And as most of 

 these are more or less closely allied to animals which 

 enjoy the full light of day, one of the first things that 

 strikes one is why they have given up the joys of an 

 ordinary existence, to pass, what appears to us to be, a 

 miserable life in total darkness. "Whatever be the true 

 explanation of this, it is of course easy to understand why 

 they should have lost their eyes, and also the coloration 

 characteristic of their outer- world relatives. 



A curious parallel exists between the inhabitants of 

 caves and those creatures dwelling in the dark abysses of 

 the ocean depths ; both living in situations entirely cut 

 ofi' from the smallest trace of daylight, and both being 

 descended from animals living either in air or water under 

 the ordinary conditions. In one point, however, a remark- 

 able difference exists between the two. Cave-animals, 

 as already said, are content to crawl or swim in Cimmerian 

 darkness, whereas the finny and other denizens of the 

 depths of the ocean possess organs giving forth a brilliant 

 phosphorescent light, and likewise other organs by which 

 they can perceive such light, and are thus able to see and 

 capture their prey with ease. In the absence of such 

 artificial light and special modes of vision, cave-animals 

 are of course compelled to rely solely on their organs of 

 touch, hearing, and perhaps of smell ; and, to our thinking 

 at least, their life must be far more dreary and devoid of 



