36 



HARDWICKE'S SCIENCE-GOSSIP. 



On the afternoon of the Sth August, I had a pretty 

 clear view of the head unobscured by the annulus. 

 The four processes were approximated like the 

 fingers of the hand, whilst the fifth or terminal lobe 

 lay away from them like a thumb (Fig. 3S). Pro- 

 jecting into the bay between the thumb and the 

 fingers, and crossing the latter obliquely, there was 

 faintly visible another process which I was unable to 

 follow further. On the other side of the umbilical 

 stalk, now worn down to a conical stump, a dense 

 crescentic streak of yoke had been as it were detached 

 and carried away by the growth of the tail till it 

 came to occupy the northern curve of the bay. 

 This included yolk, according to Kowalevski, marks 

 the extent of the mesenteron, in this case about a 

 fourth of the whole alimentary canal. The incurved 

 portion of the tail was free from the annulus, and 

 its growth seemed to be caused by the formation 

 of the dorsal half of the body carrying along the 

 ventral segments with it. In the tail this dorsal 

 portion increased much in size beyond the ventral, 

 both in length and thickness. Up till its full growth 

 the dorsal section of the abdomen had been without 

 segmentation, but, in the afternoon of the 8th August, 

 I observed it to be crenate externally ; and that the 

 indentations corresponded to the lines of division of 

 the ventral segments. That portion of the dorsum 

 extending beyond the venter and beyond the last 

 crenation opposite the last ventral segment, was 

 much larger than any other division, and showed 

 itself a crenate division into three, of which the last, 

 much narrower than the others, I supposed might 

 turn out to be the anal proleg, whilst the penult 

 crenation would represent the anal flap. I thought 

 also I could trace the posterior section of the 

 alimentary canal terminating in the space between 

 the anal flap (?) and the proleg (?) In the evening of 

 the same day I was able to distinguish four prolegs 

 on the anterior abdominal segments, near the point 

 of flexure, but could not see whether one or two 

 segments intervened between them and the thoracic 

 legs. On the Sth also, in the evening, the remote 

 group of eye-spots became dimly visible through the 

 transparent head. At first, directly opposite one 

 another, the two groups of eye-spots diverged more 

 and more till they came to be situated at the lateral 

 borders of the head, and between, and rather in 

 advance of them, a cupid's-bow-shaped line (Fig. 39) 

 appeared to indicate the anterior border of the 

 clypeus. The direction of this torsion of the head 

 was always such that, whether the embryo was lying 

 on the right or left side, its effect was to bring the 

 dorsal aspect of the head next the free unattached 

 side of the egg, and the under surface next the glass. 



Unfortunately my observations were brought to an 

 untimely close by an accident on the morning of the 

 9th, so that the last stages, as well as the earlier, 

 both of which should have much of interest to offer, 

 escaped me. I believe, however, that what I have 



been fortunate enough, thanks to Mr. Jeffrey's 

 kindness, to see, is not without some interest and 

 importance from its bearing on two points : the 

 orientation of the embryo in the shell, and the 

 incurvature of the tail. If there were any certainty 

 of obtaining similar eggs another season, I would 

 have reserved some of the other points for further 

 observation : as it is, I cannot refrain from mentioning 

 the hypothesis that, as plants are bent to or from the 

 light by a preponderance of growth on the opposite 

 side, so, here, the proximate cause of the ventral 

 curvature of the tail end is the later, but then 

 quicker and predominant growth of the dorsal section 

 of the embryo. 

 Milford, Letterkenny. 



SOME NEW DIATOMACEOUS FORMS 

 FROM THE "SAUGSCHIEFER" OF 

 DUBRAVICA. 



By F. Kitton, Hon. F.R.M.S. 



HERR GRUNOW in his " Beitriige zur Kent- 

 niss der fossilen Diatomaceen Oesterreich- 

 Ungarn" (" Beitrage zur palaontol. Oester-Ungarns 

 und d. Orients von Majsisovics u. Naumayr," Bd. 

 ii. 1882), describes the following diatomaceous 

 deposits found in Hungary: (1) " Saugschiefer " 

 (absorbent slate) from Dubravica ; (2) Polierschiefer 

 Tallya ; (3) the argillaceous tufa from Holaikluk - T 

 (4) diatom deposit from Kis-ker ; (5) Kieselguhre 

 from Eger and Franzenbad in Bohemia. The last 

 named deposits are generally well known to Dia- 

 tomists (particularly that found in Franzenbad). 

 Ehrenberg described many of the forms in the 

 " Monatsberichte " of the Royal Academy of Berlin, 

 1840, which are afterwards figured in his " Micro- 

 geologie." His figures of Campylodiscus clypeus have 

 been frequently copied. 



The Hungarian deposits were almost, if not 

 entirely, unknown until the recently published in- 

 vestigations of Herr Grunow, which, unfortunately, 

 are not readily accessible to Diatomists, excepting 

 by the purchase of the volume of the work (at a cost 

 of 40 marks) in which they appeared. Having 

 through the kindness of a correspondent been 

 enabled to examine one of the most interesting of 

 them, viz. that from Dubravica, I have identified 

 most of the species named in the list which 

 accompanied the sample. The deposit is some- 

 what delusive ; from its general appearance we 

 should suppose it would be easily cleaned ; but this 

 is not the case ; when boiled in acids the material 

 split up into thin laminae of sufficient tenuity to 

 allow of mounting without further manipulation ; to 

 separate the diatoms a careful boil in dehydrated 

 soda is necessary to dissolve the silicic acid which 

 cements the diatoms together. This cementation 



