740 



SCIENCE. 



[Vol. II., No. 44. 



visual ceHs exist in these cases. I now call to mind 

 the cases of Ostrea and Serpula. When the former 

 has its purplisli tentacles extruded from between its 

 valves, and the latter its crown of cirri extended 

 from its tube, if the hand is made to move rapidly 

 over the water in the aquarium in a strong light, so 

 as to cast a shadow upon these organs, both these 

 animals appear to be sensitive to the movement, and 

 independent of any jars or vibrations. The oyster, 

 under these circumstances, at once retracts its sensi- 

 tive mantle-border; the worms, their cirri. 



Upon examining the end of the siphon of Mya 

 arenaria, lines of pigment are found about the bases 

 of both the inner and outer circlets of tentacles, and 

 the upper end of the siphon is pfgmented for about 

 an inch, both inside and outside. On the outside, 

 however, there are scattered low, minute, pigmented 

 papillae just under the epidermis and in the pig- 

 mented layer or true skin covering the siphon. The 

 questions now arise. What is the nature of these 

 organs ? and do not the habits of Ostrea, as above 

 described, justify us in expecting to find rudimenta- 

 ry end-organs on the mantles and siphons of mol- 

 lusks, answering the pui-pose of eyes, as appears to 

 be the case in the instance of Solen? Mya, like 

 Solen, in life has normally the end only of the siphon 

 exposed: and visual powers, developed to a certain 

 degree, would therefore be useful to the animal; for, 

 when the siphon is extended above the level of the 

 sand, there are several fishes with mouths and teeth 

 well suited to nip it off, and which would doubtless 

 actually take advantage of the lielpless clam, if it 

 could not appreciate their approach. 



I find fishes much more sensitive to sudden vibra- 

 tions established in the water in which they live 

 than to shrill or grave sounds made in the surround- 

 ing air near by. This may be due to special powers 

 of perception which they may possess on account of 

 the development of the singular end-organs of the 

 lateral hue. 



The study of dermal, terminal nerve-endings, modi- 

 fied as more or less specialized sensory apparatuses 

 throughout the different groups of the animal king- 

 dom, is bound to yield many important results in the 

 near future, in addition to what is already known; 

 and the writer is glad that the matter has been taken 

 up by such competent hands. John A. Eydbk. 



Nov. 27, 1883. 



Probable occurrence of the Taconian system 

 in Cuba. 



Last year, while making two excursions aorossithe 

 mountains of eastern Cuba, between Baracoa and 

 the southern coast, I had an opportunity to make 

 some observations on the geological structure of these 

 mountains. The rocks composing this end of Cuba 

 fall naturally into three distinct groups, as follows : 

 1. Ancient, and for the most part coarsely crystalline, 

 basic eruptive rocks ; 2. Older stratified rocks, slates, 

 schists, and limestones; 3. The post-tertiary lime- 

 stones or elevated coral-reefs. 



The eruptive rocks form the main mass of the moun- 

 tains at most points. They appear on the shore in 

 some places, and seem to be almost the only rocks 

 found at greater distances than five or ten miles from 

 the coast. The older stratified rocks occur principally 

 in two irregular belts running parallel with the coasts, 

 and lying one on either side of the great eruptive 

 belt : hence they are found mainly on the flanks of the 

 miountains. The stratified rocks, especially along 

 their contact with the eruptives," are penetrated by 

 numerous irregular masses and dikes of the latter. 

 But tliat they are all older than all the eruptives is 



improbable, since the eruptives are lliemsolves evi- 

 dently of several distinct ages. 



So far as I have observed, the stratified rocks are 

 all alike unfossiliferous; and in consequence the 

 precise determination of their stratigraphic positions 

 is a difficult problem. I am satisfied, liowever, that 

 some of them are widely separated in time. The 

 newer beds, consisting chiefly of fissile slates, soft 

 sandstones, and impure earthy limestones, are prob- 

 ably equivalent to the secondary and tertiary strata 

 of San Domingo and Jamaica. These uncrystalline 

 sediments occur chiefly on the northern slope of the 

 mountains, and, although much disturbed and un- 

 dulating, rarely exhibit high dips. 



But on the south side of the dividing-ridge, or sum- 

 mit, I crossed a belt six to eight miles wide, ro.iching 

 almost to the coast, of highly inclined crystalline 

 schists. The stratification is usually distinct, the 

 strike being parallel with the coast, or east-west. The 

 schists are generally greenish, and are both hydro- 

 micaceous and chloritic. Associated with the schists 

 are several immense beds of white crystalline lime- 

 stone. The limestone undoubtedly belongs to the 

 same series as the schists, and is often micaceous. 



These i-ocks bear a strong resemblance to the Ta- 

 conian system of western New England, and are essen- 

 tially identical with the great series of semi-crystalline 

 schists and limestones of Trinidad and the Spanish 

 Main which I have elsewhere correlated with the Taco- 

 nian. 



The published reports on the geology of San Do- 

 mingo and Jamaica show that the geologic structure 

 of tiiose islands is essentially similar to tbat of east- 

 ern Cuba. In each case there is a prominent axis of 

 old eruptive rocks, flanked on either side by schists, 

 slates, limestones, and other sedimentary formations, 

 and by elevated coral-reefs. In San Domingo and 

 Jamaica the eruptives are not wholly basic, but much 

 granite occurs; and the metamorphic schists, which 

 appear to be similar to those of Cuba, have been gen- 

 erally confounded with the cretaceous beds. I pre- 

 dict, however, that more careful study will show that 

 they are distinct and vastly older, and that the Great- 

 er Antilles are similar in composition and structure 

 to the southern coast of the Caribbean Sea. includ- 

 ing the Spanish Main and Trinidad, except that the 

 coral-reefs and the eruptive rocks are wanting in 

 the latter region. We owe the coral-reefs largely to 

 the great vertical movements of the Greater Antilles 

 in recent times; and the eruptive rocks are but a con- 

 tinuation westward, and the older and more eroded 

 portion, of the great Caribbee belt of volcanic rocks 

 which begins a hundred miles north of Trinidad, and 

 ends in Cuba, being about fifteen hundred miles long, 



W. O. CitOSBY. 



THE RESTORATION OF ANCIENT 

 TEMPLES. 



The Parthenon: an essay on the mode hy tchich light 

 teas introduced into Greek and Roman temples. By 

 James Fergusson, CLE., D.C.L., LL.D., etc. 

 London, Murray, 1883. 8-1-135 p., 60 illustr., 

 4 pi. 4°. 



Only a small portion of this book is devoted 

 to the wonderful edifice from which it is named. 

 It is in the main a reiteration of peculiar views 

 concerning the lighting of ancient temples, — 

 an amplification of theories advocated thirty- 



