HARDWICKE'S SCIENCE-GOSSIP. 



175 



any of the students of his field-class to find with 

 what affectionate enthusiasm they regard him. The 

 present volume is in reality the notes made by the 

 students themselves, and is a sample of their note- 

 books and records of observations. It is a capital 

 digest of Professor Seeley's lectures on these occasions. 

 The book is illustrated by capital sections drawn by 

 Mr. Nicol Brown. It is a record of honest work 

 earnestly done, and is therefore both a vade-iitecum 

 and a stimulant to all those who desire to explore 

 the interesting geology of the London district for 

 themselves. 



Outlines of Field Geology, by Professor A. Geikie 

 (London : Macmillan). This is the fourth edition 

 of Professor (now Sir Alexander) Geikie's well- 

 known and popular little book. "We have no 

 hesitation in saying it is the best of its kind ever 

 issued. No other authority is so capable of teaching 

 field-work, considering his position as the Chief of 

 the Geological Survey, and none other is more ready 

 to teach. The present fourth edition has been 

 thoroughly revised and considerably enlarged, and 

 there is much in it which is new, especially that part 

 giving an account of the schistose rocks. New 

 illustrations have also been added where necessary. 



Among the Butterflies, by B. G. Johns (London : 

 Isbister & Co.). We are pleased to see Mr. Johns 

 so capably following his father's footsteps as a good 

 naturalist. The present little volume is handsomely 

 got up, and the twelve plates, which contain sixty- 

 seven figures of our English butterflies, are excellent 

 specimens of natural history wood-cutting. Mr. 

 Johns is possessed of much literary ability, and tells 

 his story pleasantly and gracefully. This ought to 

 be a very popular little book. 



The Human Epic. Cantos I.-V., by J. F. Row- 

 botham (London : Kegan Paul & Co.). The author 

 of this suggestive poem is an old contributor to 

 Science-Gossip. He has already won his spurs as 

 an acknowledged poet ; and this, his latest book, 

 affords fresh evidence of the natural insight which 

 all genuine poetry possesses. Tyndall somewhere 

 says that the rhythmical movements of the molecules 

 of a drop of water, and their relations to the 

 mysterious and unknown forces governing them, if 

 even baldly told, transcend in dramatic interest a 

 book in " Paradise Lost." Mr. Rowbotham is one 

 of the first of the younger school of poets to see the 

 vast advantages which science holds out of subjects 

 for poetic treatment. Tennyson made the discovery 

 half a century ago. Mr. Rowbotham heads the five 

 cantos of his "Human Epic" as follows: "The 

 Earth's Beginning," "The Origin of Life," "The 

 Silurian Sea," "The Old Red Sandstone," "The 

 Age of Trees." Geology is full of natural poetry, 

 and the author is a good geologist, as well as 

 " Scholar of Balliol College, Oxford." We cordially 

 commend Mr. Rowbolham's charming cantos to all 

 nature-lovers. 



ROSSENDALE RHIZOPODS. 



No. 4. 



THE genus Centropyxis is also a very common 

 form here, and from the writings of others, 

 appears to be widely distributed. I find it in almost 

 all my collecting-places, the various wells, ponds, and 

 ditches furnishing well-marked varieties. It is closely 

 related to Diffiugia ; and indeed it is frequently 

 impossible to determine to which of the two a 

 particular specimen may belong. The shell is of 

 various shades of brown, and is composed of 

 chitinoid membrane, incorporated or covered with 

 a variable proportion of quartz-sand or diatoms ; the 

 latter, however, I do not find so frequent a con- 

 stituent of these shells as in the genus Difflugia. The 

 greater number of those having a diatomaceous cover- 

 ing, I procure from several shaded wells where those 

 algse are plentiful. From Sphagnum, most of the 

 forms of this genus have had' the chitinoid membrane, 

 either straw-coloured or a pale, smoky brown, some- 

 times with a few scattered sand-grains, more 

 frequently entirely without. In my experience the 

 shells of this variety are very shallow. The brown 

 membranous base connects this genus with Arcilla. 

 In the ordinary form, the test appears on the dorsal, 

 on ventral aspects, sub-circular or ovoid ; but on a 

 side view, which is not quite so frequently jjresented, 

 it will be seen to be deepest behind the mouth ; in 

 other words, the mouth and top of the shell are 

 eccentric in opposite directions. In this particular it 

 resembles Diffhtgia constructa, so much so indeed, as 

 to be with difficulty distinguished from it. The 

 chief points of differences between the two are that 

 Centropyxis is more decidedly brown, is not so high 

 from the mouth to the fundus, and the margin of the 

 inverted mouth is prolonged into two or more append- 

 ages. The drawings will help to make clear the 

 form and general appearance. It will be seen that 

 on a side aspect it is somewhat cap-shaped, being 

 highest behind the oval opening. The most common 

 form has a variable number of spines, more or less 

 divergent, from two to nine^ placed laterally and 

 dorsally. These are of the brown basal membrane 

 only. The mouth is large, sub-circular, deeply 

 inverted, and according to Professor Leidy, the 

 margin is produced in one or more appendages. 

 This is generally, from the opaqueness of the shell, 

 impossible to make out, and I have myself never 

 been able to demonstrate the peculiarity, though I 

 have had hundreds under observation at various 

 times. In no case can it be seen, except in the 

 lateral aspect of the shell, and only then in specimens 

 of clear chitine, free from sand-grain. Size from 



m to --m of 'in inch. 



Fig. 152. A very common form here, of linear 

 and navicular diatoms ; with spines. 



