115 
MONSTRILLA and the CYMBASOMATIDA. 
By I. C. THompson, F.L.S. 
With Plate IV. 
[Read April 11th, 1890.] 
In a paper entitled ‘‘ Notes on the Genus Monstrilla ” 
by Mr. G. C. Bourne, in the current number of the 
“ Quarterly Journal of Microscopical Science” (February 
1890), the author refers to the various recorded species 
belonging to this genus, of which he considers my genus 
Cymbasoma to be a synonym. 
As stated by Mr. Bourne, previous to the capture of the 
solitary specimen to which I gave the name Cymbasoma * 
rigidum no similar animal had been recorded since that 
described by Claus as Monstrilla heligolandica in 1863. I 
subsequently found Cymbasoma in tow-nettings taken about 
Malta, and again in British waters on two occasions off 
Puffin Island as well as in Clyde gatherings. Mr. Sinel has 
also taken a number of specimens at Jersey, Mr. W. S. 
McMillan has found it at Torquay, and several specimens 
were taken by Canon Norman and Mr. Bourne at Ply- 
mouth. So that there has been no lack of material 
recently upon which to discuss the correctness of previous 
observations; and I may say at the outset that I concur in 
the general conclusion of Mr. Bourne that, under our exist- 
ing knowledge, the various species seem to belong to one 
. genus, and that the name Cymbasoma must be withdrawn 
in favour of Monstrilla; but, as I shall show further on, 
* Linnean Journal, vol. xx., p. 145. 
