Jan. 19, 1888] 



NATURE 



275 



modification of the spermary of the host is simply a concomitant 

 circumstance of the parasitism. It seems hard to believe that 

 the simple presence of the packets of Crustacean ova in the 

 brood sac of an Amphiura would lead to a destruciion of the 

 ova of the brittle-star, but it does not seem impossible that the 



lult Crustacean could have spayed the Amphiura. 



'\:\.\Q character of this phenomenon is so unusual that one 

 hesitates to accept it on insufficient data. There are gaps in 

 my observations which may be serious to the theory. In the 

 first place, it has not been observed that the Crustacean spayed 

 the Amphiura. The ovarian gland of the brittle-star is de- 

 stroyed, and indications point to the Crustacean as the culprit. 

 Secondly, it is not known that the parasite enters the brood sac 

 through the genital slits to deposit the ova. Thirdly, the ditlfi- 

 cuUies of determination whether the ova are in the body cavity, 

 stomach walls, or brood sac, are very great. I believe it is 

 probable that they are in the brood sac. Lastly, the family 

 nam» of the strange parasite who repays hospitality so un- 

 graciously is unknown. There is no doubt that it is a Crus- 

 tacean, as I have traced the egg through a nauplius into an 

 adult. 



As this condition of life is believed to be a novel one, and 

 needs verification, the writer takes this opportunity to call the 

 attention of marine zoologists to it, and to request corre- 

 spondence from anyone who may have made similar observa- 

 tions. Before we can definitely accept the conclusions towards 

 which my observations lead, there is a call for re-examination 

 and verification of the observations. The most important 

 questio 1 is to determine whether or not the ova of the Crus- 

 tacean live in the brood sac. 



Cambridge, Mass., U.S.A. T. Walter Fewkes. 



Raised Beaches v:rsus Higli-Level Beaches. 



If you can find space for the subjoined list of shells from the 

 ancient beach o;i the Thatcher rock in Torbay, it may prove 

 acceptable to such geologists as interest themselves i;i the 

 qaes'ion recently resuscitated by Prof. McKenny Hu^^hes, as to 

 whether the ancient Devonshire beaches are "raised," as com- 

 monly suppjsed, or merely high-level, as some hold them to be. 



Added to the late Mr. Godwin Austen's " Hope's Nose" list, 

 my list runs up the total number of species from the two beaches 

 to forty-six, and this without reckoning Mr. Godwin Austen's 

 Cardlum tuberculatum, which I think must have been an over- 

 sight for C. tchini'.um. This number has not, I believe, been 

 beaten by any British raised beach hitherto. 



Wiien the Thatcher beach was accumulated, the northern 



.11 Trophon truncatus was abundant in the neighbourhood ; so 

 was Tellinx baUhlca, a shell which only occurs, I believe, in this 

 vicinity, in or near the tidal harbours of Torbay. 



Tne Thatcher collection evidences the great an'iquity of the 

 beaeh, a considerab'e change of temperature, differences in the 

 rock -components of the cjast-line, and variatio;i in its contour, 

 or these subjects I hope sone day to treat, but in the meantime 

 the facts so far as they have been ascertained are presented to 

 geologists in the fallowing list of shells for them to deal with as 

 they please : — 



OstTjea edulis 

 Pinna rudis 

 Mytilus edulis 

 M. modiolus 

 Nuctda nucleus 

 C irdiuin cciiiiiatuni 

 C. edu'e 

 C. mrvegicum 

 Cyprina islandica 

 ■ Aitarle sulcata 

 yienus exoleta 

 V. fascia 'a 

 V. gaUinx 

 Tellinx balthica 

 L 'Uraria elliptica 

 Mictra su '■truncata 

 Sy.en vxginx 

 Mya arenaria 

 Saxlcavx ru^osa 



Patella vulgala 

 Trochui zizyf>hinus 

 Lacuna putcolus 



Litorina oblusata 

 L. rudis 

 L. liter ea 

 Turritella terebra 

 Salaria lurloncB 

 Nxtica alderi 

 Adeorbis subcarinatus 

 Cerithium reticulata 

 Pupura lapillus 

 Btccinum undatum 

 M'.irex erinaceus 

 Trophon truncatus 

 Fusus gracilis 

 F. jeffreysianus 

 N issa reticulata 

 N incrasata 

 Pleuro'omx striolala 

 P. brachystoina 

 P. turricula 

 Cylichna cylindrasa 



42 species. 



The shells have been identified in odd lots and at different 

 times by the late Mr. Gwyn Jeffreys, Mr. J. T. Marshall, and 

 Mr. D. Pidgeon, to whom my warmest thanks have been due. 

 The b.ilk of the work has, however, been done by the last- 

 naned gentleman, without whose hearty co-operation, both in 

 searching the beach material and naming the shells and frag- 

 ments found therein, the list would have been shorn of much of 

 its goodly proportions. A. R. IIUNT, 



Torquay, December 28, 1887. 



Vegetation and Moonlight. 



The letter of your Trinidad correspondent, given in Nature, 

 vol. xxxvi. p. 586, referring to a Committee appointed to deter- 

 mine moon influence, has a practical interest for me. Among the 

 wood-cutters in Cape Colony, both east and west, there is a 

 fixed belief, which no arguments can turn, that to cut timber at, 

 or shortly after, full moon, is to cut it when the sap is up ; and 

 when, consequently, it is out of season. The same belief pre- 

 vails in various parts of Southern India, notably in Travancore. 

 I have always combated the belief, pending time and oppor- 

 tunity to test it, indulging in the provisional hypothesis that the 

 bush-workers' belief may be due to the fact that they can only 

 work by night at or near full moon ; and that at night trees 

 should contain more sap than by day, when watery exhalation is 

 active. 



It seems possible that in the habitually cloudless nights of 

 certain countries the moon may exert influences not noticeable 

 elsewhere. It is well known in Cape Colony that fish, pork, 

 and other provisions go bad if left exposed to moonlight ; 

 though possibly this may be due to the light acting as a guide to 

 insects. D. E. HuTCHiNS, 



Cape Colony, December 8, 1887. Conservator of Forests. 



Centre of Water Pressure. 



Dr. Routh has done me the favour of pointing out that in 

 the first volume of his "Rigid Dynamics" he has given the 

 following very simple result with regard to the centre of pressure 

 of a triangle occupying any position in a liquid : — -"This point 

 is the centre of gravity of three particles at the middle points of 

 the sides, with masses p/oportional to their depths." 



This result of D . Rouih's is one of many very remarkable 

 theorems of integration published by him in the Quarterly 

 Journx', No. 83, iSS5. George M. Minchin. 



A New Magnetic Survey of France. 



It should not be difficult to do foreigners justice without be- 

 littling our own countrymen, and a fortiori without robbing any 

 of the latter of their birthright. 



In Prof Thorpe's paper in last week's Nature there occurs 

 the sentence, " Even the surveys of their own country (France) 

 have been made for them by Germans and Englishmen." This 

 sentence taken in connection with the opening paragraph of the 

 paper conveys the unfortunate impression that Von Lamont, the 

 author of the " Untersuchungen iiber die Richtung und Starke 

 des Erdmagne'ismus . . ." and of numerous other similar works, 

 was a German, the truth being that he was merely a " Scot 

 abroad " (see Nature, vol. xx. p. 425). T. M. 



Bothwell, Glasgow, January 14. 



TIMBER, AND SOME OF ITS DISEASES} 

 V. 



IT has long been known that timber which has been 

 felled, sawn up, and stored in wood-yards, is by no 

 means necessarily beyond danger, but that either in the 

 stacks, or even after it h.is been employed in building 

 con5tru:tion, it may siffer degeneration of a rapid 

 character from the disease known generally as "dry-rot." 

 The object of the present paper is to throw some light on 

 the question of dry-rot, by sum;iiarizing the chief results 

 of recent botanical inquiries into the nature and causes of 

 the disease— or, rather, diseases, for it will be shown that 

 there are several kinds of " dry-rot." 



' Continue .1 from p. 254. 



