288 SEXUAL RELATIONS OF 



It should be observed that the evidence in this summary 

 is of a cumulative nature. If we think it highly, or in 

 some degree probable, — from the ordinary form of Ibla 

 Cumin gii having been shown on good evidence to be ex- 

 clusively female, — from the absence of ova and ovaria 

 in the assumed males of both species of Ibla, at the period 

 when their vesiculae seminales were gorged with sperma- 

 tozoa, — from the close general resemblance between the 

 parts of the mouth in the parasites and in the Iblas to which 

 they are attached, — from the differences between the two 

 parasites being strictly analogous to the differences be- 

 tween the two species of Ibla, — from the generic character 

 of their prehensile antennae, — and from other such points, 

 — if from these several considerations, we admit that these 

 parasites really are the males of the two species to which 

 they adhere, then in some degree the occurrence of para- 

 sitic males in the allied genus Scalpellum is rendered 

 more probable. So the absolute similarity in the antennas 

 of the males and hermaphrodites both in S. vulgare and 

 S. Peronii; and such relations as that of the relative 

 villosity of the several species in this same genus, all 

 in return strengthen the case in Ibla. Again, the six- 

 valved parasites of S. Peronii and S. villosum are so closely 

 similar, that their nature, whatever it may be, must be the 

 same ; hence we may add up the evidence derived from 

 the identity of the antennae in the parasite and her- 

 maphrodite 8. Peronii, with that from the antennae in 

 the male S. villosum, approaching in character to Polli- 

 cipes, to which genus the hermaphrodite is so closely 

 allied ; and to this evidence, again, may be added the 

 singular coincident absence of caudal appendages in the 

 male and hermaphrodite S. villosum. If these two six- 

 valved parasites be received as the complemental males 

 of their respective species, no one, probably, will doubt 

 regarding the nature of the parasite of S. rostratum, in 

 which the direct evidence is the weakest ; but even in this 

 case, the particular point of attachment, and the state of 

 development of the valves, form a link connecting in some 



