ON THE DEVELOPMENT OF BILHAltZIA H/EMATOBIA. 639 
second paper to the Wiener Medicinische Wochenschrift . It is 
thus quite evident that this paper by Bilharz—one of the two 
foreign authors justly characterised by Dr. Harley as 
“ talented observers ”—is attributed by him to an altogether 
independent writer having the name of Derseble, which, as I 
have explained, should have been written derselbe. In the 
interests of truth and accuracy, it is necessary to correct 
these serious mistakes; but I may remark that, if it had 
only occurred to some one or other of the learned 
“Fellows of the Society appointed by the Council as 
referees of papers” to have drawn the author’s attention 
to them before going to press, the Transactions of the 
Royal Medical and Chirurgical Society would have de¬ 
served none the less credit for bringing out and doing full 
justice to Dr. Harley’s otherwise useful and valuable con- 
tributions. 
When fully developed, the eggs of BilJiarzia licematobia are 
more or less oval, commonly measuring from to -j-J-/' in 
length, with an average transverse diameter of • Some 
few are a trifle larger, whilst many others are much smaller. 
Occasionally one encounters remarkably narrow specimens, 
and also aberrant forms presenting a decidedly obovate or 
pear-shaped outline (Fig. a). I have met with eggs not 
exceeding m their long diameter, and-g-^/' transversely, 
whose yelk contents nevertheless had already arrived at an 
advanced stage of segmentation. 
The shell is transparent, of a brown colour, and free from 
any markings, lines, or sculpturing. One pole of the shell is 
invariably narrower than the other, and usually presents a 
more or less pointed extremity. This narrow end commonly 
displays a sharp, projecting, beak-like spine (Fig. a, c , d, j, 
k), Very constantly the base of the spine rests upon the 
central point of the pole of the shell (Fig. k) ; but not unfre- 
quently the process is eccentrically placed (Fig.*#). In some 
few examples, the spine is removed to a little distance from 
the actual extremity of the shell; but even in these instances, 
so far as my observations go, its apex always projects beyond 
the level of the curved end of the pole. It is difficult to 
avoid the conclusion that the figures showing the markedly 
lateral disposition of the spine represented by Leuckart and 
Bilharz are not somewhat exaggerated ; nevertheless, I have 
frequently witnessed an approach towards the extreme 
degree of side disposition which they describe. Sometimes 
the spine is altogether absent (Fig. b) ; and, when present, 
it is, as I have already hinted, very unequally developed. In 
size, it ranges from a mere point having an extreme length 
