96 Mr H. Goodsir on the Sexes of the Cirripeds, 8^c, 



ration. The organs of locomotion are situated round the mouth, 

 and to a considerable extent act as organs of respiration. The 

 young of both are endowed with organs of vision, which in 

 after life become extinct — in all cases in the Cirripeds, and 

 in almost every instance in the LernsDse. 



These facts will shew the near connection which the two 

 sets of animals have to one another, and that it is a more 

 close relation than that of mere analogy which exists between 

 them. In fact, the Cirripeds may be considered as Lerna?3P, 

 the former being attached to animate, the latter to inanimate 

 bodies. This last assertion, however, is not altogether cor- 

 rect, inasmuch as we find species of Cirripeds attached to the 

 skins of the Cetacea. 



There are some other points of similitude between the male 

 Cirriped and the Crustaceans, but these are of less note. It is 

 connected to the Podothalma by means of its eyes ; and to the 

 Isopoda by means of the structure of its feet, and the anterior 

 division of its body. 



The natural size of this animal is (when the organs of ge- 

 neration are at their highest state of enlargement) about a line 

 in length, and a line in breadth. In some cases, however, it 

 is rendered much larger from being infested with a parasitic 

 crustacean. This parasite is an Isopod belonging to the family 

 loniens of M. Edwards, and which will form the type of a nevv 

 genus in that family. (Plate III., Fig. 7). 



Of this parasite, we shall now proceed to give a short descrip- 

 tion. It infests the soft part of its victim only, and sometimes 

 in very considerable numbers. When brought under the field 

 of the microscope, it was found to belong to that section of the 

 Isopodous crustaceans, termed by M. Edwards, the Sedentary 

 Isopods. It is about the fourth of a line in length, almost colour- 

 less, except in the middle of the body, where it is of a dark 

 brown colour. The body consists of seven segments, of which 

 the second appears to be the longest ; this one, however, seems 

 to be also articulated, although very indistinctly, and is pro- 

 bably composed of five segments instead of one, seeing that the 

 five pairs of legs arise from this part of the animaFs body. 



A long triarticulate antenna arises from each side of the 

 first segment near to its posterior and external angle. The 

 two first joints are the thickest, and both of them conjoined 



