FAMILY SPHAHROMIDA. 77 
Isocladus (Miers), and Zuzara (Leach). In a specimen 
with marsupium, but without brood, of an undetermined 
species of Exospheroma from Victoria, I find, very distant 
from the mesial line and rather near the base of the marsu- 
pial lamelle, four pairs of low tubercles at the hind margin 
of second to fifth sternites; each tubercle has a small longi- 
tudinal slit at its outer side. Being acquainted with this 
structure, it was possible with 50 degrees of enlargement to 
find in Zuzara integra (Hasw.) at least three pairs of nearly 
microscopical rounded apertures in the same situation as the 
small slts in the Hxosphzeroma mentioned, but in some 
specimens with brood of Exosph. lanceolatum (White) 
and Isocladus spiniger (Dana) it was impossible to discern 
apertures with any reasonable degree of certainty, though 
they must be present. While the structure and the wander- 
ing of eggs and young are easily understood in Spheroma 
and Cymodoce, the minuteness of the apertures of the 
pouches in the other genera mentioned is a serious difficulty, 
perhaps connected with some undiscovered structural feature. 
Among the eubranchiate Spheromine some genera, viz. 
Scutuloidea (Chilt.), Paracerceis(n. gen.),and Cassidi- 
nopsis (n. gen.) have their brood in internal pouches, but the 
number and position of the apertures has not been examined. 
Of Dynamene (Leach) (sens. strict)' I have seen three 
females of two European species. The marsupium, which 
covers the entire lower surface of thorax, is filled either with 
eggs or with young not arrived at maturity ; the marsupial 
lamellee, especially the posterior pair, are exceedingly large. 
The whole arrangement is nearly asin Limnoria lignorum 
(Rathke) ; the number and size of eggs and young evidently 
differ little from those in the last-named species. Nesicopea 
1 Not being able to decide whether Nasa (Leach) or Dynamene (Leach) 
ought to be used for the European genus, I applied to my friend the Rev. 
T. R. R. Stebbing, who is specially versed in such questions. He sent me, 
most courteously, a very detailed exposition, but as he added that he was 
working on Spheromide, and his results are to be published, I accept his 
decision that Dynamene must be preferred, and refer the reader to the 
proofs to be found in his future paper. 
