SCIENCE. 



235 



A NEW ROTIFER. 



In a filtering of Hemlock lake water (Rochester's water 

 supply) made in August of last year, I noticed a rotifer 

 that at once struck me as different from any that I had 

 before observed or seen described. On classification it 

 proved to be a Brachionus, and a diligent search through 

 the somewhat scattered literature on the subject has since 

 failed to satisfy me that this form has ever been described. 



7-1000ths of an inch. 



Brachionous Conium. 



The Micrographic Dictionary uses the classification of 

 Ehrenberg, while Carpenter in his work, " The Microscope 

 and its Revelations," adopts that of Dujardin. While 

 all classifications of the Rotatoria' thus far made are in 

 some ways unsatisfactory, that of Ehrenberg seems the 

 least faulty, and according to it I find that this organism, 

 by reason of having its rotary disk divided into two parts 

 (jZygotvechd) and having a carapace, would show that it 

 belongs to the family " Brackionaa." There are five 

 genera in this family. The Brachionus has one eye-spot 

 and forked foot, and to this genus the rotifer unquestion- 

 bly belongs : " Brachionus Conium." 



Lorica irregularly truncate, slightly reticulated over en- 

 tire surface except the collar carrying frontal spines ; this 

 latter portion has a hard vitreous appearance. 



Ten frontal spines, the middle one on the dorsal sur- 

 face longer than the balance and describing almost a 

 right angle turn near its center to one side. This spine 

 half as long as the carapace of the rotifer. Eye-spot 

 prominent. No openings on dorsal surface of carapace. 



Four posterior spines, one at either extreme side and 

 one on either side of anal opening. Tail or foot, slender 

 and bifid. Extreme length of rotifer including anterior 

 and posterior spines, seven one-thousandths (7-ioooths) 

 of an inch. 



Unfortunately a dead specimen had to be used for the 

 drawing, hence no definite description can be given of 

 mouth parts for internal structure. The external appear- 

 ance is, however, so strikingly characteristic as to serve 

 all purposes of identification until the internal structure 

 can be fully described. H. F. ATWOOD. 



MICROSCOPICAL NOTES. 



The subject of standard screw gauges was recently 

 brought before the R. M. S., and the question of the ac- 

 curacy of 50 duplicates, made for distribution, was dis- 

 cussed. Mr. Bevington considered " they were as near the 

 standard as could be expected." Mr. Beck pronounced 

 them on trial to be defective. It seemed to be conceded 

 that the original " taps and dies " had been lost, but as 

 Mr. Crouch thought that the present set of duplicates 

 was sufficiently perfect for all practical purposes, we 

 suppose opticians must rest and be thankful for what they 

 can obtain. Considering the deterioration, which must 

 occur from the wear and tear of the cutter, it is to be re- 

 gretted that perfect accuracy cannot be given to the 

 standard gauges issued by this society. 



On the presentation of a paper by Mr. Shrubsole on the 

 " Diatoms of the London Clay," the President, Professor 

 Martin Duncan, made the following interesting statement 

 on the subject. He said that "those who studied this 

 class of subjects would be greatly interested in the paper 

 which had been brought before them ; and no doubt 

 had it been read before the Geological Society, there 

 would have been considerable discussion upon it. The 

 London clay had at the bottom of it large beds of 

 pebbles ; these were all water-worn, and clearly indi- 

 cated an old shore. Just above this, on a sinking 

 shore like it, would be precisely where they should ex- 

 expect to find diatoms. But the London clay just above 

 this became a little more marine, and this fact would 

 account for their not finding these fresh-water forms 

 there also. Then it should be remembeied that the oc- 

 currence of diatoms was subject to great variations, 

 and that they were always found in greatest abundance 

 in the neighborhood of silicious rocks. As regarded their 

 age, he thought there could be no doubt that they lived at 

 the time of the Lower Eocene. Theie were, however, some 

 peculiarities about the London clay, there being no other 

 strata which were deposited under the same conditions, 

 because it was not a reef deposit, but it positively told 

 the story of an open estuary leading down to a very 

 large river. This was one reason why they would not 

 find the diatoms in similar deposits in Italy or W T ales. 

 It was not an uncommon thing to find that in other 

 fossils the carbonate of lime was replaced by sul- 

 phide of iron. Phosphate of lime was often also re- 

 placed by sulphide of iron, and the interstices of other 

 fossils were often found filled with the same substance, 

 which was an exceedingly common mineral in the Lon- 

 don clay. Silica was not the difficultly-solgble substance 

 which it was formerly thought to be, so that its place 

 could be as easily filled up by any other mineral which 

 was less soluble than itself — from which consideration he 

 thought the matter might be explained. But when they 

 came to the question of antiquity, it was not so easy to 

 give an opinion as to whether Count Castracane's 

 diatoms in the Carboniferous series were with good 

 reason thought to be diatoms. In the Tertiary of course 

 they found them ; but if Count Castracane's propositions 

 hold good, we ought to be sure to rind them in the inter- 

 mediate series." 



Mr. Shrubsole said Mr. Kitton's idea was that they 

 were fresh water diatoms which had been washed down 

 into the coal-beds. 



The President expressed himself unable to accept such 

 a suggestion. 



Last week the Whittaker Court Marshal was con- 

 tinued, and Dr. Piper of Chicago, was examined as an 

 expert on Microscopy. In cross-examination questions 

 were submitted to the witness on the construction of the 

 Microscope, which Dr. Piper admitted were beyond his 

 knowledge. One question related to the composition of 

 the glass used for the construction of lenses for the 

 Microscope. 



Possibly few Microscopical experts could answer 



