Dec. 7, 1871] 



NATURE 



[03 



find its service increase in importance as he makes his way into 

 the highest parts of the subject. 



Of course no attempt is liere made to attack D-ism, but to 

 state that it and Dot-ism have their proper splieres, tlie latter 

 generally, with more or less appropriateness, throughout the 

 whole realm of functions, the former in the realm of motion, 

 where the functions are functions of / — the sway over which 

 realm was originally given to it by Newton, and acknowledged, 

 as I have been told, by the D-ist Lagrange. 



Glasgow College Thomas Muir 



Occurrence of the Eagle Ray 

 A DOUBLE-SPINED specimen of the eagle ray (Myliobaiis 

 aquila), taken in Torbay on the 1st Nov., has been presented to 

 this museum by Mr. Frank Gosden, fish dealer, High Street, 

 Exeter. Its dimensions are as follows : — Breadth across the fins, 

 2ft. 3lin. ; length from snout to the base of the spines, 

 I ft. 7|in. ; total length from snout to extremity of the tail, 

 3ft. 64in. W. S. M. D'Urban, Curator 



Albert Memorial Museum, Exeter 



Deep Sea Dredging 



While winter allows of time for complete arrangements to be 

 made in anticipation of dredging weather, will you permit me to 

 raise the question of the conditions under which our knowledge 

 of the natural history of the sea may be most readily extended ? 



As a rule, yacht owners object to the fatigue and dirt of 

 dredging, but as we have the successful example of the Noma, 

 may we not hope that other yachts may further the cause of 

 science, if assistance] in the way of instruction or apparatus be 

 afforded to them by those having the necessaiy experience and 

 means ? 



The idea of now urging the question is not mine alone, but is 

 entertained by many ardent naturalists who are much in favour of 

 a skilful search of our seas at home, as well as of the Mediter- 

 ranean and other distant and almost untried seas. 



Your pages have often borne witness to the interest and 

 importance attaching to marine zoology, and if men of practical 

 experience, such as Carpenter, W. Thomson, Marshall Hall, 

 Sic. , will indicate the best localities for search and the best mea- 

 sures to adopt, we may hope that others may follow in their steps, 

 and that the large aquaria now built and building will be sup- 

 plied, as only private zeal and enterprise can compass, with new 

 and rare specimens from deep waters. 



T. H. Hennah 



Milton House, Clarence Street, Brighton, Dec. 5 



The Solar Halo 



The solar halo of the morning of the 13th ult. described in 

 your last number as seen near, and at about thirty miles from, 

 Durham, and which Prof. A. S. Herschel conjectures may have 

 been seen from more distant stations, was visible here. 



I first saw it at about S .v. M. , when it appeared as the arc of a 

 circle, witli a very short portion of an inverted arc touching it at | 

 the vertex — the sun itself being hidden by a bank of cloud, from \ 

 behind which issued several radiatmg spikes. Shortly after half- 

 past nine this halo had disappeared, except a small portion at 

 the point of contact of the two arcs, vertically over the sun, \ 

 which appeared like a bright elongated patch, forked at edch ' 

 end, and projected not on mist, but on blue sky, and tinged with 

 dull prismatic colours, which were most strongly marked in the j 

 inverted arc, in which the red or orange was downwards, or on 

 the outside of the circle. I then suddenly caught sight of a 

 second halo, of much greater radius than the first — visible through 

 perhaps 130^ or 140" of arc, above, and to the right of, the sun, 

 projected on the clear blue sky, but so faintly that it might easily 

 have been missed. This outer circle exhibited the prismatic 

 colours with a purity and delicacy that I have never before seen 

 in halos, and which was quite different to the ordinary dull, 

 muddy colours. In fact, it had just the appearance of a very 

 faint and narrow rainbow, the red being inside, and the blue 

 outside the circle. I was shortly after able to borrow a sextant, 

 and measured the distance from the sun to the bright patch and 

 the outer circle, which appeared respectively 21 ' 40' and 43' 20' ; 

 but they were already growing so faint that I was unable to 

 do this with much precision. Except the bright patch before 

 named, I did not observe any appearance of "mock-sun." 



Cardiff, Dec. 4 Geo. C. Thompson 



ON THE ZIPHIOID WHALES 



'T'HE peculiar division of Cetaceans to which the term 

 ■•- " Ziphioid " is now commonly applied, from one of 

 the earliest known forms, Ziphius of Cuvier,* is in 

 many respects one of the most interesting of the order. 

 They form a very compact group, united closely together 

 by the common possession of very definite structural 

 characters, and as distinctly separated from all other 

 groups by equally definite characters. 



With the singular exception of Hyperoodon rostratus 

 (the structure and habits of which species are as well 

 known, perhaps, as those of any other cetacean), no spe- 

 cimen of the group had ever come under the notice of 

 any naturalist up to the commencement of the present 

 century. Since that tiine, however, at irregular intervals, 

 in various and most distant parts of the vvorld, solitary 

 individuals have been caught or stranded, now amounting 

 to nearly thirty, these being by some naturalists referred 

 to upwards of a dozen distinct species and to very nearly 

 as many genera. No case is recorded of more than one 

 of these animals having been observed at one place at a 

 time, and their habits arc almost absolutely unknown. 

 Their very presence in the ocean seems to piss unnoticed 

 and unsuspected by voyagers, and even by those whose 

 special occupation is the pursuit and capture of various 

 better known and more abundant cetaceans, until one of 

 the accidental occurrences just alluded to reveals the 

 existence of forms of animal life of considerable magni- 

 tude, and at least sufficiently numerous to maintain the 

 continuity of the race. 



This comparative rarity at the present epoch contrasts 

 greatly with what at one time obtained on the earth, espe- 

 cially in the period of the crag formations, and leads to 

 the belief that the existing ziphioids are the survivors of 

 an ancient family which once played a far more important 

 part than now among the cetacean inhabitants of the 

 ocean, but which have been gradually replaced by other 

 forms, and are themselves probably destined ere long to 

 share the fate of their once numerous allies or proge- 

 nitors. 



The Ziphioid whales belong to the great primary divi- 

 sion or sub-order of the Odontocetes or Toothed whales, 

 as distinguished from the Whalebone whales. They are 

 allied on the one hand to the Cachalots or Sperm whales, 

 and on the other to the true Dolphins and Porpoises, but 

 more nearly to the former than the latter. They are 

 animals varying between fifteen and thirty feet in length, 

 and in external characters very closely resemble each 

 other, all having small pointed snouts or " beaks," small 

 rounded or oval pectoral fins or "flippers,'' a coinparatively 

 small triangular dorsal fin, situated considerably behind 

 the middle of the back, and a single " blowhole " of con- 

 centric form, situated in the middle of the top of the head 

 One of their most obvious characteristics, distinguishing 

 them from the true dolphin, is the complete absence of 

 teeth (except occasionally a few mere rudiments concealed 

 in the gum) in the upper jaw, while in the lower jaw there 

 is usually but a single pair, which in some species may be 

 greatly developed and project like tusks from the mouth, 

 though sometimes even these are rudimentary and covered 

 up by the gum, so that the animal is practically toothless. 

 In addition to these external and easily-recognised charac- 

 ters, there are others connected with the skeleton and 

 internal organs which separate them still more trenchantly 

 from the other members of the order. Their food appears 



* " J'appliquerai au genre dont elle (a skull found on the shore of the 

 Mediterranean) devient le premier type, le nom de Ziphius, employe par 

 quelques auteurs du moyen age (Voyez Gesner I., p 209) pour un cetace 

 qu'ils n ont point determine " ( Cuvier, "Osseiuens fossiles '*). According to strict 

 rules of pr ority ''Hvperodontoid" would be the more correct term, as 

 Hyperoodon was the first genus of the group distinctly characterised : but as 

 the name is erroneous in its signification, it will be better to keep to the more 

 generally adopted and less objectionable term of " Ziphioid," first applied by 

 Gervai.s. The group is equivalent to Eschricht's " Rjiynchoceti." 



