ME. P. H. GOSSE ON THE DICECIOUS CHAEACTEE OP THE EOTIEEEA. 325 
both the sexes, is the only example in which I have not seen the penis ; but the organ 
is probably wholly retractile within the body, and my observations, on the only indivi- 
dual of this sex that I saw, were insufficient to determine anything concerning it. 
45. For a parallel to the curious facts thus established we must look only to the 
Ceustacea. The economy of the Hectocotylus of certain Cephalopod Mollusca, though 
perhaps even still more abnormal, is only remotely analogous. Nor is the parallelism 
very close of those Entozoa in which the males are organically united to the females, 
as the genera Heteroura and Syngamus, described by Professor Owen*. 
46. In the Class Ceustacea, however, many examples occur of a sexual difference, 
which may instructively be compared with the one before us. Thus, among the Isopoda, 
we find the parasitic genera Bopyrus^ PJiryxus, and lone, in which the males are notably 
smaller than the females, very diverse in form, and in some respects inferior in structure. 
In the Siphonostoma “ the males are extremely small, and do not in the least resemble 
the females f,” though those of different genera bear a strong resemblance inter se, even 
when the females are very dissimilar. So low is their grade of organization, that Bue- 
MEISTEE has attempted to prove these muiute creatures to be embryonic or larval forms. 
And, finally, in the Cieeipedia, Mr. Daewin has proved the existence of males in the 
genera Ibla and Scalpellum, which are very minute as compared with their females, 
excessively abnormal in form, and in some respects in an embryonic condition, though 
unquestionably mature, as shown by the spermatozoa J. And, what is still more inter- 
esting, the same accurate zoologist observes, — “ After the most careful dissection of very 
many specimens I can venture positively to assert that there is no vestige of a 
mouth, or masticatory organs, or stomach §.” Again, he describes the internal structure 
as “ a pulpy mass with numerous oil-globules,” and the sperm-vesicle as “ a pear-shaped 
bag at the very bottom of the sack-formed animal, containing either pulpy matter, or a 
great mass of spermatozoa || ,” — terms which might have been employed in describing 
some of the male BracMoni (§ 26, &c.). 
47. In all these analogies I conceive we may find additional reasons, to those that have 
been before adduced, for assigning to the Kotifeea a zoological position among the 
Aeticulata. 
Explanation of the Plate. 
Plate XV. 
Fig. I. Brachionus Bala ; male egg, nearly mature. 
Fig. 2. Brachionus Bala ; male, newly born. 
Fig. 3. B. rubens ; male egg, nearly mature. 
Fig. 4. B. rubens ; spermatozoa from the same egg. 
Fig. 5. B. rubens ; male, newly born. 
Cycl. of Anat. and Physiol, p. 142. 
J Monograph of Lepadidse, 198. 
t Baied’s ‘ Entomostraca,’ 325. 
§ Ibid. 235. II Ibid. 236. 
