Oct. 20, T887] 



NA TURE 



591 



"granulitic group." Descriptions of these various localities are 

 given, and illustrative specimens are exhibited. The crystals of 

 feldspar are f nind to be most numerous in those rocks which lie 

 in the closest proximity to the gabbros and serpentine. They 

 have their long axes at various angles, and are mostly small 

 •except at Parn Voo=;e, Cavouga, and Green Saddle. The feld- 

 spathic and hornblendic lines often circle round the crystals. 

 Without discussing any theory as to the true nature and origin 

 •of the whole of the schists, the authors think that the porphyr- 

 iiic structure so prevalent in the dark bands of the " granulitic 

 group," in many of the micaceous and other rocks, as also in 

 the later intrusions cutting the serpentine, indicates an igneous 

 ■origin for many rocks hitherto regarded as schists. 



Preliminary Observations on the Geology of Wieklow and 

 Wexford, by Prof. Sollas. — Of rocks older' than the Cambrian, 

 examples probably occur in the Carnsore district, but most of 

 the presumed Archaean rocks are to be explained as crushed 

 igneous dykes and flows. The Cambrian are certainly uncon- 

 formably succeeded by the Ordovician. The main granite of 

 the district is a truly intrusive rock, but at its junction with the 

 Ordovician, which it penetrates, it possesses the characters of a 

 tnie gneiss, the schi-tosity of which corresponds in direction 

 •with that of the adjoining schists, having resulted from earth- 

 movements which took place after the Ordovician and before the 

 Lower Carboniferous period. 



Some Effects of Pressure on the Sedimentary Pocks of North 

 Devon, hy ]. E. Marr. — The structures described in this paper 

 are mainly seen in the Ilfracombe division of the Devonian 

 system, as exposed near the bathing place at Ilfracombe. The 

 rocks there consist of argillaceous beds, with thin bands of grit 

 and crinoidal limestone ; these harder beds are folded into a series 

 ■of small sigmoidal folds, which form portions of similar larger 

 folds. When the middle limb is replaced by a fault, the cores 

 of the folds remain as "eyes" of limestone or grit, and these 

 " eyes " have undergone further modification, having been pulled 

 out into thin lenticular masses. In this way we have all the 

 mechanical structures of a true schist produced (including the 

 apparent false-bedding), the rock now consisting of clay-slate 

 xvith altemating folia of grit or limestone, or both. Quartz 

 veins are folded in a similar way to that described above, and 

 the final result of this folding appears to be the production of a 

 rock consisting of alternating clay-slate, limestone, and quartz- 

 folia. Every stage of the process is seen in the case of the 

 limestone "eyes." The cores of limestone, when not dragged 

 out, have their compound crinoid stems pressed into polygons, 

 which have been formed in the way descriloed elsewhere by Dr. 

 Sorby. When the lime^^tone is pulled out the stems are separ- 

 ated, as in the case of the Belemnites figured by Heim, and the 

 intervening portion is filled with calcite. In this neighbourhood, 

 then, we find sedimentary rocks presenting all the mechanical 

 peculiarities of normal schists, without any great amount of 

 chemical change. 



On the Organic Origin of the Chert in the Carboniferous 

 Linustone Series of Ireland, and its Similarity to that in the Cor- 

 responding Strata in North Wales and Yorkshire, by Dr. George 

 Jennings Hinde. — The author showed that this rock, which has 

 hitherto been usually regarded as an inorganic deposit of silica 

 direct from the sea water, is in reality made up of the micro- 

 scopic detached spicules <<{ siliceous sponges. These sponges 

 lived in successive generations over certain areas, and, after the 

 death of the sponges themselves, the minute spicules forming 

 their skeletons fell apart and were strewn over the bottom of the 

 Carboniferous seas in countless numbers, .so that by their 

 accumulation beds of solid rock wiih a total thickness of from 

 150 to 350 feet have been formed. Sponges were thus more 

 important as rock formers in the Carboniferous than at any 

 subsequent geological epoch. 



On the Affinities of the so-called Torpedo {CycXohaiK, Egerton) 

 from the Crettucous of Mount Lebanon, by A. Smith Wood- 

 ward. — Following Egerton's original determination, the fish 

 seems to have been universally regarded up to the present time 

 as referable to the Torpedinidae, partly on account of its rounded 

 shape, and partly on account of the supposed absence of dermal 

 defences. The fine series of specimens now in the British 

 Museum, however, appears to demonstrate conclusively that 

 these generally-accepted views as to the affinities of Cyclobatis have 

 no sure foundation in fact, but that the genus is truly referable 

 to the Trygonidcc. There is thus no evidence, as yet, of the 



existence of "electric rays" of an earlier date than those made 

 known by Volta and Baron de Zigno from the Eocene of .Monte 

 Bolca, near Verona, in Northern Italy. 



The Pliocene Beds of St. Erth, Cornwall, by Robert George 

 Bell.-— The opinion expressed in the earlier reports upon this 

 deposit, as to the southern facies of its fauna, has been amply 

 justified by fresh researches. Had there been any connexion 

 with northern seas or colder waters, it would b; difficult to 

 understand the entire absence of those forms of Pleurotoma 

 (Bela) so abundant in the Boreal seas of the Crag period and the 

 present age, as well as the equally characteristic bivalves, 

 Astarte and Cyprina. Some conflict of opinion exists upon the 

 depth of water in which the St. Erth clays were deposited. In 

 a letter to Nature, vol. xxxiv. p. 341, a very competent 

 authority on Pliocene phenomena, Mr. Clement Reid, gave it as 

 at least 40 or 50 fathoms, founding his view on the evident fact 

 of its deposition in still water, which he maintains could not be 

 found in a district exposed to Atlantic swells at less depth. To 

 this the writer must take serious exception. Undoubtedly the 

 clays exhibit an entire absence of such a disturbing cause as the 

 influence of great wave action, but it remains to be proved that 

 such a great depression as Mr. Reid describes did occur at the 

 western end of Cornwall, and as far as the author's observa- 

 tions go there is little indication of such a fact. Some depression, 

 of course, must have happened, sufficient to submerge the low- 

 lying land near St. Erth, causing a strait or gulf, dividing the 

 Land's End from the main eastern portion of the county. In 

 this shallow strait the clays and sands were deposited, and just 

 such an assemblage of Mollusca is found as will bear out this 

 view. Scarcely any of the shells which are of living species are 

 known to inhabit such deep water as Mr. Reid indicates, while 

 the majority show the presence of a laminarian zone, extending 

 to not more than 15 fathoms. 



On a Starfish from the Yorkshire Lias, by Prof. J. F. Blake. 

 — The specimen described was an external cast of the underside 

 of a Solaster, which was sufficiently well preserved to afford 

 both generic and specific characters. The only known species 

 with which it is comparable is Luidia murchisoni. If this is 

 truly described, and is in fact a I^uidia, then the present s]3eci- 

 men, which is certainly a Solaster, must belong to a different 

 species. It was found at the base of the cliff at HuntclifT by 

 the Rev. G. Crewdson, of Kendal. 



The Classification of the Dinosauria, by Prof .Seeley, F. R.S. 

 — The author discussed the structure of the animals named 

 Dinosauria, and concluded that the group had no existence, the 

 constituent animals belonging to two orders which have no near 

 affmity ; they are named Omosauria and Cetiosauria, the former 

 with a sub-avian pubis and ischium, the latter with those bones 

 sub-lacertilian. The Omosauria is defined as having the ventral 

 border of the pubic bone notched out, so that one limb is directed 

 backward parallel to the ischium, while the other is directed for- 

 ward. The ilium has a slender prolongation in front of the aceta- 

 bulum. The Cetiosauria is defined by having the pubes directed 

 forward with a median symphysis, but with no posterior limb to 

 the bone. The anterior prolongation of the ilium has a vertical 

 expansion. 



On the Reputed Clavicles and Interclaviclcs of Iguanodon, by 

 Prof. H. G. Seeley, F. R.S. — The author showed, by superim- 

 posing a figure of the reputed clavicle upon the bone figured by 

 Mr. Hulke as clavicle and intcrclavicle of Iguanodon {Quart. 

 Journ. Gcol. Soc, vol. xli. plate xiv. ), that the supposed sutures 

 are fractures, and that the supposed interclavicle has no exist- 

 ence, except as an ossification posterior to the reputed clavicles. 

 Then it was urged that these bones are unparalleled by any verte- 

 brate clavicles, while the reputed pubes of crocodiles and pre- 

 pubes of other animals ofler a more probable analogy. The 

 ossificati m in front of the pubis in Ornithosaurus is of similar 

 form in several genera. And in crocodiles the ossification of the 

 fibrous extension which connects the reputed pubes with the 

 sternal ribs would produce a bone like the supposed interclivicle 

 of Iguanodon. Hence it was urged that these bones in Iguano- 

 don are prc-pelvic, and the author identified them with the 

 pre pubic bones. 



On the Permian Eauna of Bohemia, by Prof. Anton Fritsch 

 (of Prague). — After having mentioned the seventy-three species 

 of Labyrinthodonts of which he has giveu figures in his work 

 (" F.auna dcr Gaskohle "), and of which he exhibited the electro- 

 types and restored models in the galleries of the Owens College, 



