HARDVVICKE'S SCIENCE-GOSSIP. 



Ill 



Baker's student's quarter is a most excellent lens 

 for ihe price. Swift has also lately introduced some 

 capital glasses at a moderate cost, particularly his 

 ^ and -J. None of these objectives possess the high 

 angular aperture of the costly glasses of Ross, 

 Beck, Powell and Leland, and others, but where 

 only a moderate angle is required, they are all 

 that can be desired. The apparatus that may be 

 considered almost a necessity are as follows : — Spot 

 lens ; Luberkiihn's, to powers below i inch ; dark- 

 wells and holders, extra eyepiece ; bull's-eye con- 

 denser; disc of diaphragms ; the entire cost would 

 range from about £12 to £16; a cheaper stand and 

 dividing objectives would cost about £5 to £10;' 

 anything of less cost would be of little practical use. 

 — Z, Kitton. 



Microscopic Analysis. — I should be obliged 

 by some of your numerous correspondents giving 

 me a few practical details for the preparation of 

 powders, &c., previous to their examination micro- 

 scopically for analytical purposes. I can find no 

 directions in any of the manuals. This subject is 

 becoming an imx)ortant one for public analysts.— 

 B. G. Lomdx. 



The Eozoon Controveesy. — The debate as 

 to the organic origin of this object has been again 

 revived, through an article whicli appeared in a 

 recent number of the Annals and Magazine of 

 Natural History, by Mr. H. J. Carter, in which 

 that gentleman expressed his disbelief in the 

 animal origin of Eozoon, founded on a specimen he 

 had examined. In the last number of the same 

 magazine. Dr. Carpenter returns to the charge, and 

 writes what we consider the best and clearest 

 article he has yet given on the subject. After 

 perusing Dr. Carpenter's paper, it is difficult to 

 turn away the conclusion that Uozoon was a true 

 foraminil'er, abnormal in many respects, but not 

 more so than the Farkeria of the Greeusand. In 

 the same number is an abstract of a paper by 

 Prof. Max Schultze, on the Eozoon Canadense, in 

 whicli that celebrated microscopist gives the result 

 of his own examination of original specimens, and 

 the conclusion he has arrived at is that there can 

 be no serious doubt as to the foraminferous nature 

 of Eozoon. 



ZOOLOGY. 



The Relationship between the Echino- 



THUKID^ (WyVILLE ThOMSOn) AND IHE PeEI- 



schoechinid^ (McCoy).— At a recent meeting of 

 the Geological Society, a paper on the above sub- 

 ject was read by R. Etheridge, jun., P.G.S. The 

 author referred in the first place to the peculiar 

 characters of the genera Culver iu and Pkormoscma, 

 Wyville Thomson, and especially to those in v.hich 



they' approach the cretaceous genus HcJiinothuria, 

 S. P. Woodward, and which led Prof. Wyville 

 Thomson to include these three forms in his group 

 Echinothuridaj. He remarked that an overlapping 

 of the interambulacral plates, more or less like that 

 occurring iu these three genera, is met with also in 

 Archceocidaris, McCoy, and Lepidechinus, Hall, 

 belonging to the group of palaeozoic Echini, which 

 McCoy proposed to call Perischoechinidse, and 

 which is characterized by the presence of more 

 than three rows of plates in the interambulacral 

 areas. As there is no overlapping of these plates 

 in the other geuera referred to this group, it includes 

 two types of structure. The author then discussed 

 the characters presented by the test in the genera 

 of the Perischoechinidse (namely Archceocidaris, 

 Palaxhinus, Perischodomus, Lepidechinus, Eocidaris, 

 Melotiites, and Oligoporus), and pointed out that 

 although we have no conclusive evidence of the 

 presence of membranous interspaces along with the 

 overlapping plates in Archceocidaris, the fragment- 

 ary condition in which the remains of that form 

 are usually found would lead us to infer their exist- 

 ence. No known palaeozoic genus exhibits the 

 want of distinction between the ambulacra and 

 interambulacra on the ventral half of the test seen 

 in the recent genus Phormosoma. In Melonites and 

 Oligoporus the author described an increase in the 

 number of rows of plates in the ambulacra, and 

 he indicated that all the Perischoechinidse differ 

 from the later Echini by the increased number of 

 perforations in the ocular and genital plates. In 

 the discussion which followed the paper, Mr. Ethe- 

 ridge, sen., described Calveria as resembling an 

 elastic ball rather than an ordinary Sea-urchin, its 

 calcareous plates being held in place by a flexible 

 membrane, and as connecting the ordinary forms 

 with Ecliinothuria, in which the plates slide over one 

 another like armour. He remarked that the apical 

 disks vary in each genus ; in the palaeozoic genera 

 the ovarian plates have three or more and the ocular 

 plates two perforations. The interambulacral areas 

 in the palaeozoic genera have invariably more than 

 two rows of plates. In Archceocidaris the plates 

 have bevelled edges. The chief point of the paper 

 was its indicating that a type supposed to have 

 been long extinct is still represented in our seas. 

 Mr. Seeley observed that the buccal membrane in 

 the recent Echinida has overlapping plates, so that 

 if the development of the plates usually forming the 

 remainder of the test were arrested, forms would be 

 obtained approaching those described in the paper. 

 He stated that in his opinion both the Echinoderm 

 type and the Brachiopod tj'pe have analogies with 

 the Annelids. Mr, H. Woodward remarked thai; 

 of the Holothuridse some forms, such as Psoliis, are 

 protected by calcareous plates having perfect free- 

 dom of motion. Mr. Gwyn Jeffreys added that 

 Calveria hijsirix was dredged off the Faroe Island?, 



