64 



HARD WICKE'S S CIENCE- G SSI P. 



has also long been knovm as a rich storehouse 

 of Trilobites of various species and genera. 



In the Devonian beds it is only here and there we 

 can meet with Trilobites in any abundance. One of 

 the best localities we know of is Newton Abbot, in 

 Devonshire, where the limestone contains numerous 

 Trilobites. The Pilton beds yield certain species of 

 Phacops in plenty. The Trilobites are most abundant 

 in the Middle Devonian strata of England, owing to 

 the probable fresh-water conditions under which most 

 of the other beds were deposited. The carboniferous 

 limestone, both of England and Ireland, is frequently 

 rich in Trilobites of the genei^a Phillipsia and Grif- 

 fithsides, named after two distinguished geologists. At 

 Castleton, in the Peak of Derbyshire, along the out- 

 crop of the strata forming Tre-cliff, is a band especially 

 crowded with Phillipsia ; and in the curious gorge 

 to the immediate south of the cavern called " Cave 

 Dale " (undoubtedly an ancient cavern with the 

 roof worn off ), we may find this Trilobite associated 

 with a wonderfully abundant collection of other 

 fossils. At Salt Hill, Clitheroe, in Lancashire, the 

 shales which part the limestone bands are seen 

 crowded with the evidently moulted remains of 

 Phillipsia. 



The large number of species, even of British 

 Trilobites, obtained from the various strata above 

 mentioned, are grouped into certain families. We 

 have first the Agnostidcv, characterized by their small 

 size, by the head and tail being covered with two 

 nearly equal shields, and the jDossession of not more 

 than two body-rings. This family was eyeless. The 

 Oletididic or Paradoxidiv had long bodies, with 

 numerous free segments. The caudal or tail shield 

 was small ; the side lobes were prolonged into curved 

 spines. A large number of the more ancient genera 

 of Trilobites belong to this family. The Asaphida: 

 were tolerably large oval Trilobites, with smooth 

 carapaces, and possessed about eight body-rings. 

 Illccims and Ogygia are included in this group. The 

 TrimuleidtE had a large head-shield, ending in two 

 long spines, one on each side. The body-rings were 

 five or six in number. The Cheiriiridct included 

 seven distinct genera, which had a geological range 

 from the Cambrian to the Devonian strata. The 

 facial sutures of the head-shield ended on the outer 

 margin. The number of rings or segments ^^'as 

 eleven, and these were free at their ends. The 

 CalymenidtE had carapaces roughened over with 

 granules or tubercles, and the number of body-rings 

 was usually thirteen. In Jlonialoiiotiis, one of the 

 two genera composing this family, the body-rings 

 are not so distinctly trilobed as usual. Phacopida was 

 a family of Trilobites with large facetted eyes. The 

 number of body-rings is eleven. The Lichadic had 

 small head-shields, and a tail or pygidium with a 

 broad limb. It contains only the genus Lichas. The 

 Proetida includes the carboniferous genera Phillipsia 

 and Griffithsidcs. Their number of body-rings was 



usually nine. The carapace of Phillipsia is generally 

 roughened witJi granules. Acidaspidcz had a very orna- 

 mental carapace, with eight to ten body-rings, and 

 the segments of the side lobes (pleurae) directed 

 backwards. The tail had also two or three segments, 

 furnished with prominent spines. The Bronteida: 

 had a large expanded tail or pygidium. The Harpeida: 

 were noted for the horseshoe-shaped head-shield, 

 whose angles were greatly prolonged. The body 

 was numerously jointed, usually with twenty-six 

 segments. Only one genus, Harpes, belongs to it. 

 Lastly, we have the Cyphaspidic, whose head-shield 

 was also prolonged into spines, and the carapace 

 marked by spiiiy or pitted surface ornamentations. 

 The number of body-rings varied in the different 

 genera from ten to twenty-two. These are among the 

 less common of the Trilobites. It will give us much 

 pleasure to hear from any correspondents respecting 

 habitats where any genus of species of Trilobite is to 

 be plentifully found. 



METROPOLITAN NATURAL HISTORY 

 AND MICROSCOPICAL CLUBS. 



THE following is a list of some of the clubs in 

 London devoted to natural history pursuits, 

 &c. :— 



Medical Microscopical Society (founded December, 

 1872). — This society meets at the Century Club, 6, 

 Pall-mall-place, \V., on the third Friday of each 

 month from October to May inclusive, at 8 p.m. 

 There is no entrance-fee, and the subscription is los. 

 per annum. The members are qualified members of 

 the medical profession and students of medicine or 

 compai-ative histology whose qualifications are accept- 

 able to the society. The objects of the society are 

 the discussion of questions in normal and pathological 

 histology, medico-legal and medico-chemical micro- 

 scopy, mechanical and optical arrangements requisite 

 for the proper examination of specimens, the prepara- 

 tion of the same, &c. ; the formation of a cabinet of 

 preparations for the use of members, and the ex- 

 change of specimens and matei'ial. The officers for 

 1877 are — President, H. Power, F.R.C. S., &c. ; 

 Ho)i. Secretaries, J. W. Groves, C. H. Golding-Bird. 

 South London Entotnological Society (established 

 1872). — Meets at the Assembly-rooms, 104, West- 

 minster-bridge-road, S.W. (side entrance). Presi 

 dent, i^TI, Mr. J. Piatt Barrett, Radnor-street, 

 Peckham. The society has been formed to promote 

 entomological science in South London. Meetings 

 of the members are held every alternate Thursday, 

 from 8 to 10 p.m., in the above Assembly-rooms, 

 when papers are i-ead, exhibitions of specimens made, 

 and discussions take place. A libraiy is being 

 formed as rapidly as funds will permit, all surplus 

 money being devoted to the purchase of books. The 

 society's room is easy of access from all parts of 



