272 



KNOWLEDGE 



[Decembeb 1, 1898. 



All the above-mentioned species (together with a host 

 of others) are members of the typical genus Ci/jjrcea, 

 distinguished by the smooth and shining enamel, and the 

 circumstance that the teeth of the mouth do not extend 

 across the whole of the lower surface, as shown in Fig. 1, d. 

 There are, however, other cowries differing from these by 

 the development of rugosities on the back, and the exten- 

 sion of the teeth of the mouth right across the lower 

 surface. Both these features may safely be regarded as 

 indications of greater specialization than exists among any 

 of the typical cowries. One type is represented by the 

 pustuled cowry (Fig. 1, b), in which the ornamentation on 

 the upper surface takes the form of small spherical pustules, 

 frequently of a bright red colour, when they recall a 

 fragment of wood overgrown with fungi. In the second, 

 and still more advanced modification, the ornamentation 

 of the back assumes the form of transverse ridges, which 

 in some species (Fig. 1, e) are comparatively wide apart, 

 and separated by a considerable interval in the middle 

 line, whereas in others, like the little European cowry 

 (Til till eiiropaa), they are so closely approximated, and so 

 nearly meet in the middle line, as to give the idea of a 

 small and neatly-parted head of hair. 



Even these by no means exhaust the modifications 

 which the cowry type is capable of assuming, as witness 

 the pure white " poached egg," and the " weaver's shuttle," 

 both members of the genus fhuhj, and the latter remark- 

 able for the elongation of the two extremities of the mouth 

 into tube-like processes. Both these, as well as certain 

 other allied types, depart from the ordinary cowry type by 

 their white or pinkish colour, and are therefore evidently 

 specialized modifications. In the case of the weaver's 

 shuttle the colour is probably produced to harmonize with 

 the sea-fans, upon which these molluscs are parasitic ; but 

 further information in regard to the reason for the absence 

 of colour is requisite in the case of the other kinds. 



One result of the necessarily brief dissertation on 

 cowries is to show how short-sighted was the idea prevalent 

 some years ago that the shells were of no importance in 

 the study of molluscs, and that attention must be restricted 

 to the soft parts (the so-called " animal ") alone. A wider 

 grasp of the subject shows that nothing in Nature is 

 unworthy of our best attention, and is sure to yield results 

 of more or leSs absorbing interest if only we approach 

 the subject with unbiassed and unprejudiced minds. 



Kefeeenoes to Plate. 

 PiO. 1. — a. Serpent'3-liead Cowry {Ci/praa caput-serpen f is). 



b. Pustuled Cowry {Piisfiilaria pustulata), upper and under views. 



c. Histrio Cowry (C. arabica histrio). d. Chestnut- bordered Cowry 

 (C.^ helvola), upper and under riews. e. Radiate Cowry {Trivia 



Pia. 2. — a. Scott's Cowry fCi/prma scottij, young and adult. 

 b. Surinam-Toad Cowry (C. mauritanicaj , young. 



Fia. 3. — a. Adult and Immature of Lynx Cowry {Cypnea lynx), 

 b. Wasp Cowry (C. asellus). c. Colaader"Cowry (C. cribraria). 



Fia. 4 — Immature and Adult conditions of the Lesser False Argus 

 Cowry (Ciiprcea exanthema). 



Fia. 5.— Nutmeg (aj and Map (bj Cowries (C. arabica and mappa). 



Fia. 6.— The Argus Cowry fCyprcea arqus). 



Noti(£0 of Booits. 



A Classijlcatlon of Vertehrata. By Hans Gadow, m.a., 

 F.E.S., etc. (A. & C. Black.) 3s. 6d. net. The extent 

 to which knowledge increases in all departments of scien- 

 tific study is nowhere more impressively brought home to 

 one than in the changing classifications which these 

 advances make necessary in the domains of biology. Of 



course, the practical aim of any system of classification is 

 sorting and grouping ; and the ideal system is one which 

 expresses briefly all that is known of the race history and 

 development of the creatures dealt with. To mitigate the 

 discrepancies as much as possible, chiefly owing to the 

 bewildering mass of fossil reptiles which have come to light, 

 Dr. Gadow has " arranged the reptiles in numerous sub- 

 classes, and these again in orders, while for the host of 

 fishes ' divisions,' and for the birds ' divisions ' and 

 ' legions ' have been resorted to as intermediate groups 

 between sub-classes and orders.' An interesting table on 

 p. 61 accentuates in the most marked way what has been 

 said about the necessity of elaborations in systems of 

 classification which are not very recent. The table shows 

 there are, in all, some twenty-four thousand two hundred 

 and forty- one recent species of vertebrate forms to be 

 arranged ; of these, nine thousand eight hundred and 

 eighteen are birds, and two thousand seven hundred and 

 two, mammals. The fishes number no fewer than seven 

 thousand three hundred and twenty-eight. 



Krumsiup I olour PhiAoijraphy. By Frederic Ives. ' 

 (London : The Photochromoscope Syndicate, Limited.) 

 The problem of reproducing in permanent form the colour 

 of objects is a popular one. Many attempts at solving it 

 have been made, with varying amounts of success, but 

 none of them have been successful in obtaining coloured 

 prints of natural or artificial objects. Three processes 

 which have up to the present gone farthest in this direction 

 are ; — (1) The process of Prof. Lippman, by means of which 

 beautifully coloured photographs are obtained on glass by 

 interference effects. (2) Prof. Joly's process, in which an 

 object is photographed through a glass, having fine lines 

 closely ruled upon it, coloured in the primary colours. 

 The colourless picture thus obtained is afterwards pro- 

 jected through a similar glass, with the result that the 

 colours are reproduced. (3| The Kromscup of Mr. Ives, 

 by which three negatives are taken through three glasses 

 coloured with the primary colours. These negatives are 

 afterwards combined in one picture. The colours of an 

 object are thus first analysed and then synthesised. This 

 method gives excellent results, and is the only one which 

 has so far been successsuUy placed on the market. The 

 little booklet which Mr. Ives has written gives full par- 

 ticulars concerning the construction and method of using 

 his instrument, and with the various appendices, which 

 comprise expressions of opinion on the theory of colour by 

 several physicists, should be useful in popularizing his 

 method of reproducing natural colours. 



Stories of Starland. By Mary Proctor. (Potter and 

 Putnam Company, New York ; G. \Y. Bacon & Co., Ltd., 

 London.) Miss Proctor has written a very delightful little 

 book on astronomy for children. " I like it awfully " was 

 the verdict of one small boy upon it. Very simply and 

 clearly she tells— or, rather, her little brother Harry elicits 

 from her — the principal facts about what we see in sun and 

 moon and sky in the daytime or at night. Very many 

 stories and legends, such as are told by the Indian and 

 Australian peoples, are mixed up with the sterner facts of 

 scientific astronomy, and some of these are not generally 

 known, whilst the rest will bear repetition. The story of 

 the meteor that was claimed by the landlord as flying 

 game and the tenant as ground game, the Custom House 

 authorities intervening, ought to be true if it is not really 

 so. In a book for children the illustrations might have 

 well been rendered more numerous than they really are. 

 It was a pity, too, to insert "the moon" on page 50, and 

 we must confess that we fail to recognize the aspect. 

 Perhaps, too, the fearfully complicated system of canals on 

 Mars, represented on page 71, might with advantage have 



