152 It. M. Deeley and G. Fletcher — Structure of Glacier-Ice. 



both, in size and proportions with the corresponding element in 

 QEonoscopus} Two examples of (Eonoscopus cyprinoides from the 

 Bavarian Lithographic Stone (Brit. Mus. J^os. 37795-«) are available 

 for reference, and the maxilla is tolerably well pi^eserved in both. 

 The writer has thus little hesitation in predicting that one more genus 

 will soon be recognized as common to the Purbeckian fish fauna of 

 England and the Lower Kimmeridgian fish fauna of the Continent, 

 which have long been known to exhibit the closest relationship. 



EXPLANATION OF PLATE VII. 



Fig. 1. Coccolepis Andreivsi, A. S. Woodw. — Lower Purbeck : Teffont. [Museum 



of Practical Geology.] 

 ,, 2. Mesoclon macropterus, yar. parvus, nov. — Middle Purbeck : Lime Kiln 



Quarry, Teliont. cl. clavicle ; op. operculum ; p. op. preoperculum. 



[Collection of Sev. W. E. Andrews.] 

 ,, 3. Macrosemius Andreivsi, sp. nov. — Middle Purbeck: Teffont. [Britisli 



Museum, No. P. 6303.] 

 ,, 4. Fry of FleurophoUs, showing incomplete flank-scales over vertebral 



column. — Lower Pm-beck : TefPont. [Collection of Eev. W. R. 



Andrews.] 

 ,, 5, 6. Zeptolepis Brodiei, Ag. — Lower Purbeck : Lime Kiln Qmrry, Teilont. 



c. coprolitic contents of intestine. [Collection of Eev. "W". E. 



Andrews.] 

 ,, 7, 8. Caturus tenuidens, sp. nov. ; right dentary and left maxilla, outer 



aspect. — Purbeck Beds : Swanage. [British Museum, Nos. 40657, 



P. 442a.] 

 ,, 9. (Eonoscopus, s^.; right maxilla, outer aspect. — Purbeck Beds : Swanage, 



[British Museum, No. 33477.] 

 ,, 10. Osteorachis macrocephahis, Egert. ; imperfect head, left lateral aspect, 



two-thirds nat. size. — Lower Lias : Lyme Regis br. branchiostegal 



rays; c.o. circumorbitals ; d. dentary; ecpt. ectopterygoid ; gu. gular 



plate ; mx. maxilla ; p.f. prefrontal ; pmx. premaxilla ; pt.f. post- 

 frontal ; pt.o. postorbital ; s.mx. supramaxilla ; scl. sclerotic ; spl. 



splenial. [Oxford University Museum.] 



Unless otherwise stated, the figures are of the natural size. 



(The description of Osteorachis macrocephahis, from the Lower Lias, Lyme Eegis 

 — PL VII. Fig. 10 — will appear in the May Number. — Edit. Geol. Mag.) 



n. — The Structure of Glacier-Ice and its bearing upon 



Glacier-Motion. 



By E. M. Deeley, F.G.S., and Geokge Fletcher, F.G.S. 



DURING last August the writers made a short stay in Switzer- 

 land and the Savoy, with a view to examine the structure of 

 the ice of several of the larger glaciers. For this purpose a rough 

 polariscope was used. It was so designed that a sheet of ice about 

 two inches square, made very thin by cutting and melting, could be 

 placed between the polarizer and analyzer. Notwithstanding that the 

 thin slide so prepared, and held between glass plates, melted away 

 rather rapid]}', we succeeded in making a number of drawings of 

 sections cut from the ice at different parts of the glacier, and at 

 various angles with the line of motion. In some cases, however, 



1 0. G. Costa, Ittiol. Foss. Ital. (1853), p. 2. Also described under the names 

 of Macrorhipis (A. "Wagner, Abh. k. bay. Akad. Wiss. math.-phys. Cl. vol. ix. 

 1863, p. 723), and Attakeopsis (V. Thiolliere, Poiss. Foss. Bugey, pt. ii. 1873, 

 p. 23). 



