ANATOMY OF THE TEST OF DISCOLDEA CYLINDRICA. 
61 
species. The validity of this interesting observation by Loven 
will have to be tested on other grounds ; for it is a matter of 
considerable doubt in our minds whether all the species which 
have been admitted into tbe genus Discoiclea can remain in it. 
D. subuculus differs much from D. cylindrica in the hollowed-out 
and tumid nature of the actinal part of the test, in the existence 
of low primary ambulacral plates only, and their great crowding 
without the formation of compound plates. Again, the madre- 
porite is in the second basal only. Nevertheless, we have found 
ribs on the inner surface of the actinal part of the test, as in 
D. cylindrica ; and probably the perignathic girdle will be found. 
As yet, we have only detected very indefinite traces of it. 
On the Characters of the Gfenus Lophopus, with Description of a 
new Species from Australia. By Stuart 0. Kidley, M.A., 
P.L.S. 
[Read 4th November, 1886.] 
(Plate II.) 
Probably in few groups of the Animal Kingdom have such 
unnatural characters been employed for the distinction of genera 
and species as in the Phylactolsematous Polyzoa. Pew systematic 
zoologists can, for example, have studied the relations of Alcy- 
onella and Plumatella without feeling that the current reasons for 
separating these two divisions are far from satisfactory, consist- 
ing, as expressed by Prof. Allman in his well-known 1 Monograph 
of the Preshwater Polyzoa’ (Kay Society, 1856), chiefly in the 
manner of connection between the tubes composing the colony. 
“ Except in the condition of the dermal system, the structure of 
Plumatella differs in no essential point from that of Alcyonella. 
This system, however, in the coalescence of the tubes into a 
common mass in Alcyonella , while they remain totally distinct in 
Plumatella , presents us with a difference which I believe to be 
of sufficient importance to justify us in placing the two forms in 
separate generic groups ” (Z. c. p. 92). 
Dr. Jullien (“ Monographic des Bryozoaires d’eau douce,” Bull. 
Soc. Zool. Prance, x. p. 90, published in 1885) has given very 
forcible expression to this feeling of dissatisfaction, and has 
indeed introduced into the classification modifications of a very 
LINN. JOUBN. — ZOOLOGY, YOL. XX. 6 
