Dr. R. Kossman on the Entoniscide. 83 
tissues of this is certainly very difficult, whilst after even only 
an imperfect peeling of the parasite it is quite easily dis- 
covered. : 
Fritz Miiller (1) has described in detail and figured the male 
of Entoniscus porcellane; but of that of Hntoniscus (Hntione, 
nob.) cancrorum he has only figured the abdomen (‘ Fiir 
Darwin,’ fig. 16), and devoted a few words to it in his 
*‘ Bruchstiicke’ (2, p. 55). Nevertheless his statements, as 
compared with my own results, enable us to establish those 
peculiarities of the male which distinguish the Entoniscide in 
general from the Bopyride, as well as to discriminate these 
from the mere generic characters. 
In the first place the males of all Entoniscide in common 
have only six pairs of pereiopods, and therefore remain in this 
respect in a larval stage which is passed by the Bopyride by 
the development of the seventh pair. 
Then the males of all Entoniscide seem to differ from those 
of the Bopyride by the retrograde condition of the antenne. 
Fritz Miiller (2, p. 55), indeed, says that in respect of the ~ 
structure of the antenne the male of Hntione cancrorum re- 
sembles the males of the Bopyride; but as he enters into no 
details upon this point, and gives no figure, and as, on the 
other hand, there is very much in favour of the generic 
identity of EH. cancrorum with L. Cavolinid and H. Moniezi, . 
i cannot help thinking that he must have overestimated the 
really existent differences in the antennal region of the two 
forms. At any rate H. porcellane, Cavolinit, and Moniezit 
agree in this, that in the frontal region, instead of distinct 
antenne, there is only one pair of lobe-like one-jointed pro- 
jections, which vear a group of setee at their obtuse extremity ; - 
but which pair of antennee these processes represent it is 
impossible to decide. 
_ The males of the Entoniscide have the mouth-structure 
(see fig. 5) im common with those of the Bopyride, as the 
curved, unjointed, and unpalpiferous mandibles have their 
simple apices projecting close together between the labrum 
and labium. But there are no rudiments of maxille and 
maxillipeds. As regards the pleon, the males of the Ento- 
niscide agree closely with many Bopyride; it is distinctly 
six-jointed, and at least the first five segments are destitute 
of paired appendages. ‘The internal organization agrees per- 
fectly with that of the male Bopyride, as Fritz Miiller (1) 
has already demonstrated. 
The differences between the males of the two genera Ento- 
niscus (H. porcellane) and Entione (H. cancrorum, Cavolinii, 
and Moniezit) are as follows :— 
GE 
