NOTES AND MEMORANDA. 
28 7 
directly on the skeletal structure of the fossil Stromatoporoids. 
Lastly, respecting Sponge alliance, we are beset by obstacles, for 
neither do the Horny, Siliceous, nor Calcareous divisions, recent or 
fossil, so far as present knowledge extends, supply us with stable 
data whereon to assert identity. By reason of the nature of the 
skeletal basis the two former groups are necessarily excluded ; while 
total absence of spicules in the Stroinatoporae, as widely understood, 
renders it impossible to class them unconditionally with the Calca- 
reous order of the Sponges. But seeing that Hydrozoal construction, 
with its tubular zooidal cavities, tabulEc, &c., has not been shown to 
exist in the typical forms of the Stromatoporoids, and that neither in 
3Iillepora nor Hydractinia, &c., so far as we are aware, does such a 
system of intercommunicating passages and occasionally lacunae 
without walls obtain, as exemplified in Stromatocerium, &c., we are 
constrained to adopt the parallel of the Siliceous Sponges with fused 
and adnate s^eicules, and assume the existence in times past of a Calca- 
reous group of the class Spougida with a continuous skeleton com- 
posed of non-spicular granular calcareous matter. We are, however, 
by no means prejudiced, but hold ourselves open to conviction ; for 
if hereafter it be demonstrated that the canal systems, &c., of 
the StromatoporcB are not normal j)roductions, as we at present 
believe them to be beyond any reasonable doubt, but ‘ branching 
canals bored by some low vegetable organism,’ as Moseley (1. c. 
p. 116) avers is the case in Millepora and Pocillopora, &c., and, 
furthermore, that other structural Stromatoporoid peculiarities are 
present in undoubted members of the Hydrozoa, then we shall be 
willing to admit their alliance with the latter, though certainly they 
are aberrant types. With our present imperfect knowledge, and taking 
into account all the data for and against, we must at present regard 
them as a group per se, or, as we think justifiable on the positive and 
negative evidence, a new section of the Calcareous Sponges, for which 
we propose the term Stromatoporoidea.” * 
The Compound Microscope applied to the Examination of Electric 
Discharge in Gases. — In ‘Nature’ for September 19th f is figured and 
described the microscope devised by Drs. W’^arren De La Eue and 
Hugo W. Muller for this purpose. The body of the microscope is 
composed of two tubes (that next to the eye made of ebonite, for 
protection against accidental shocks) bent at an angle for convenience 
of observation, and at the angle is placed a revolving mirror which 
can be rotated by a multiplying wheel so as to make 1000 revolutions 
in a minute. The microscope is furnished with special mechanism to 
adjust the focus and the field of view. 
Marine Excursion of the Birmingham Microscopical Society. — The 
second marine excursion took place on 19th to 27th July last, when 
twenty-eight members went to the island of Arran. A small steam 
yacht was chartered for the week ; and as the result of the dredgings 
a beautiful series of specimens was taken, including Luidia fragillisima 
* The ‘ Journal of the Linnean Soc.,’ vol. xiv. (Zool.), p. 187. 
t ‘ Nature,’ vol. xviii. p. 548. 
