32 



HARDWICKE'S SCIENCE-GOSSIP. 



coarsest of grass, to which no living animal would 

 care to give a passing glance. All the strata are cut 

 through ; when sinking a pit the rubbish is sent 

 away. When the pit gets under way, falls of shale 

 are almost of daily occurrence, and the greater part 

 of this shale has to be brought away, which soon 

 makes the heaps grow larger. The geologist will 

 perhaps find in no part of the world so rich in fossil 



Fig. 29. — Anthracosia ovata, a common fossil in coal shales. 



remains, as those refuse shale heaps, met with at our 

 colliery places. If he were to split some of the shale 

 open, he might find abundance of fossil mussels, such 

 as Anthracosia, as well as of fossil ferns and other 

 plant remains, and thus discover that even in our 

 district there is plenty of interest, although it is only 

 a Pit one ! 



John Sim. 

 North u in be r land. 



ON THE EMBRYOLOGY OF BOTYS 

 HYALINALIS. 



By Dr. J. A. Osborne. 



~\\ 7TIILST according the first place in embryo- 

 V V logical research to the method of investiga- 

 tion by means of sections, Dr. August Weismann, 

 in his latest work (" Beitr. z. Kenntniss d. ersten 

 Entwickelungsvorgange im Insektenei," Bonn, 18S2), 

 is yet of opinion that the older method, by "contin- 

 uous observation of the living and developing egg," 

 has of late years been much underrated. "There 

 are," he says (loc. cit. p. 2), "certainly phenomena 

 of development, where the method by section fails us 

 altogether, and of whose course, nay, very existence, 

 only direct observation gives us any intelligence." 

 Perhaps there are few eggs of insects which, owing to 

 their extreme flatness and transparency, are better 

 suited for direct observation during development than 

 those of Botys hyalinalis. They are small oval discs 

 of about 2" 3-2 • 5 mm. in length by 2 mm. or rather 

 more in breadth, not thicker in proportion than the 

 body of a sole or plaice is to its diameter, and thin- 

 ning off in like manner to a sharp edge at the 

 circumference. The shell is transparent as glass, and 

 the view but little impeded by the somewhat coarse 

 reticulations of the chorion in irregularly polygonal 

 fields with linear borders and uneven areas. 



On the 4th of August last, I received by post from 

 Mr. W. R. Jeffrey, of Ashford, Kent, a small batch of 

 seven of these eggs which had been laid on glass 

 some time on the morning of the 2nd. The batch 

 had a somewhat greasy whitish appearance, and on 

 closer inspection the eggs were seen to be arranged 

 in an oval or_ ring of six surrounding a central one, 

 but all overlapping, in such a manner that the central 

 egg was overlain by three at one end of the oval, and 

 overlay the three at the other end ; whilst of the 

 former three the middle (or remotest) egg overlapped 

 the other two, and of the latter three the middle (or 

 nearest) egg was overlapped by them. The lateral 

 pair of the first three also overlapped the lateral pair 

 of the second three, but the eggs of each pair did not 

 touch each other. In this arrangement there was 

 one egg (only) at the nearest extremity of the long 

 axis of the group, which lay directly on the glass 

 without overlying a part of any other ; and one 

 (only) at the other extremity of the axis, which, 

 overlying two others in part, was itself not overlapped 

 by any other. The conclusion appears inevitable 

 that these eggs were respectively the first and last 

 laid in the group : otherwise a later egg must have 

 been partially inserted beneath one already deposited 

 on the glass — a supposition which the character of 

 the eggs themselves would appear to negative 

 decidedly. I found it convenient, taking the longer 

 axis of the group as a meridian running north and 

 south, and designating the central egg as "C," to 

 distinguish the others by the points of the compass, 

 as N., S., N.W., &c, and regarding the group always 

 from the free side. The moth, then, in depositing her 

 eggs, must have proceeded along the glass in a general 

 direction from south to north ; and the eggs must have 

 been laid in the following order: — S., S.W. and S.E., 

 C, N.W., and N.E., N. The order of precedence in 

 the lateral pairs is no t determinable from these premises . 

 Subsequently Mr. Jeffrey sent me the shells of another 

 group of nine of these eggs, laid at the same time, 

 which give some further insight into the method of 

 oviposition. In this group, which has a transversely 

 elongated rhomboidal form, the extreme lateral eggs, 

 E. and W., which were absent in the first, are present. 

 Here it is plain that the eggs were laid in rows of 

 three each, forming an acute angle with the meridian, 

 and each row beginning a step further east or west and 

 further north than the row before it. The order must 

 (mostlikely)havebeenS., S.W..W. ; S.E.,C, N.W. ; 

 E., N.E.,N. ; or else, S., S.E., E. ; S.W.,C, N.E. ; 

 W., N.W., N. I enclose diagrams (Figs. 3o"and 31), 

 the better to illustrate my meaning, but if it should 

 be inconvenient to engrave these, the grouping may 

 be very well imitated with the requisite number of 

 pence or half-pence, taking the vertical line of the 

 figure on the coin to represent the long axis of the 

 egg. In all cases the long axis of the egg-oval lay 

 north and south, i.e. parallel with the meridian of the 

 group ; and, as subsequent observation showed, in 



