ON THE BRITISH EDRIOPHTHALMA. SS' 



considerably longer, and terminates with a simple opening near the centre 

 of the extremity of the tube (fig. 2 «). In Ganimarus (fig. 3 a) the orifice 

 is on one side of the terminal point, and furnished with a small bundle of 

 minute hairs. 



The spermatozoa are long simple hair-like bodies, and bear a general 

 resemblance to those found in the Cirripedift ; in Sulcator they have their 

 largest diameter at one end and the smallest at the other, but there is no 

 decided enlargement of one part over the other to give it the tadpole resem- 

 blance of the typical form of these organisms. In Ganunarus, the largest 

 part*, if one is larger than the otlier, is a little on one side of the centre, 

 with the smallest diameter equally at each extremity f. 



In the Aberrantia, a group recognized under the generally-accepted 

 synonym of Lcemodipoda, the male organs are of a more powerful character, 

 and connected in Caprella with the coxas of the last pair of thoracic legs, 

 which in this group are all anchylosed with the segment from which they 

 originate (PI. XXI. fig. 4 a). 



In the closely allied genus Prolo, the pleon (abdomen), though rudi- 

 mentary, is not so entirely obsolete ; similar appendages to those which we 

 have considered male organs in Caprella exist, four in number, but these 

 homologize with the pleopoda of the anterior pieon in tlie normal type of 

 Amphipoda. 



This fact can scarcely interfere with the adaptation of the members as 

 intromittent organs, since in the higher order of the Brachyura the vas 

 deferens is known to pass directly into one of the false feet, modified for a 

 similar purpose. The observations oii this family are further supported by 

 those of M. Rousel de Vauzeme, on Cyamus ovalis\, in which the organs 

 are situated analogous to those of Caprella. 



Organs of Reproduction {female). — If we found that to become acquainted 

 with these organs in the male required much care, those of the female demand 

 it still more, a circumstance which will account for the incompletion of all 

 their details with this Report ; but we feel assured that which we here state 

 may be relied upon as correct as far as it goes. 



In the normal type of the Amphipoda, hitherto we have failed to discover 

 the vulvai, but infer its place from the fact of their constant position in all the 

 higher forms of Crustacea, on the coxje of that pair of thepereipoda or walking 

 legs, attached to the fifth segment of the pereion; and we are induced to assign 

 them an analogous position. In the Brachyura they are generally described 

 by authors as perforations in the sternum ; so they appear also in the abnor- 

 mal ^wjo^eporfa {Caprella) : in both these cases, as has been proved, the coxae 

 are fused with their supporting segments. lu Homanis, &c., where the coxas 

 are free, the vulvae are seen in their normal position, which we believe to be 

 homologically constant in Crustacea ; and those in the Amphipoda, probably 

 being only oviducts in their adaptation, have escaped our observation from 

 some slight obstruction to our plan of inquiry. 



* We have observed minute objects like fat-globules attached to these thread-like organs 

 \yith which they were in contact, or else form a part of the structure ; a few in fig. 5 are 

 drawn with the spots attached. 



t The description given by Von Siebold in his ' Anatomic Comparee,' p. 472, § 290, agrees 

 generally with the forms here alluded to. He says, moreover, that they are very similar in 

 Mysis and the Isopoda. This statement is made by him on the authority of observations on 

 Mysis, Oniscus, Porcellio, Idothea, and Gammarus (Von Siebold, Miiller's Archives,1836); and 

 Kolliker has observed the same, but states them to be rigid, and not in a figure of 8, as 

 observed by Siebold in Iphimedia obesa and Hyperiu medusaria, where they are slightly 

 enlarged and a little bent at^ne extremity. 



t Ann. des Sciences Nat, 1834. 



