192 ZMZISOZEXiXj-A-IsrEOTJS. 



Geology of Cambridgeshire. — Mr. Whitaker has just published 

 a list of works on the Geology of Cambridgeshire (printed for the 

 Woodwardian Museum, Cambridge). It contains titles of 121 works ; 

 which is, however, a small list in comparison with those relating to 

 other counties which he has prepared. 



Discovery of a New Species of Fish of the Genus Aorolepis 

 IN the Millstone Grit of Yorkshire. — At the monthly meeting 

 of the Manchester Geological Society, held on the 27th of January 

 last, Mr. John Aitken, F.G.S., of Bacup, exhibited and described a 

 number of very fine specimens of fish of the genus Acrolepis, new 

 to science, which he had obtained from the debris brought out in 

 excavating a tunnel through Wadsworth Moor, in the neighbour- 

 hood of Halifax, in a bed of fine black shale, separating the third 

 from the fourth or Kinder Scout Grit, — the principal specimens 

 having been obtained from nodular concretions which abound in the 

 shales at this horizon. 



The specimens comprise two nearly perfect heads (in the jaw of 

 one a tooth is exhibited in situ), and several parts of the body illus- 

 trating the form and structure of the fish, amongst which are remains 

 of two or three fin rays. The scales and head-plates are beautifully 

 ornamented and covered with a fine enamel, — the former being 

 rhomboidal in form, and profusely sculptured, having a number of 

 distinct waving ridges and furrows traversing them in the direction 

 of their longest axis, varying in nimiber according to the position 

 they occupied on the body of the fish, the ridges having a strong 

 tendency to bifurcate, and not unfrequently to further subdivide into 

 two or three branches, these often again converging and becoming 

 re-united. 



The genus Acrolepis has been figured and described by Professors 

 Agassiz, McCoy, and King, the specimens having, with the exception 

 of that by McCoy, been olDtained from the Magnesian Limestone of 

 this counti'y and Germany. The specimens exhibited have, however, 

 much larger scales, and differ in the stjde of ornamentation, as well 

 as in many other essential particulars, from any of the figures re- 

 ferred to, leaving no doubt as to their constituting a new species of 

 this rare fish. The discovery also carries this genus into a new 

 horizon, which has previously been considered as almost barren 

 ground : it is now known to be co-extensive with the Carboniferous 

 system, ranging from the Mountain Limestone, through the Millstone 

 Grit and Coal-measures, into the Permian formation, where it appears 

 to have attained its maximum development; its remains having 

 been found there more plentifully, both in our country and on the 

 Continent, than in any of the older members of the system. 



It is intended shortly to have the specimens described and figured, 

 so that palceontologists may have an opportunity of judging of the 

 value of the discovery. 



In addition to the specimens above referred to, Mr. Aitken also 

 exhibited remains of four or five other genera of fish, viz. Acanthodes 

 sp., C'ladodus, Rhizodus (? Ctenacanthus) , and Pcdceoniscus, together 

 with a considerable variety of other fossils, all from the same locality. 



