CALIGOIDEA. 



1347 



other side presented their usual appearance. This singular derange- 

 ment was observed in a full-grown female, which was perfect in all 

 its other organs. 



An additional peculiarity, as yet inexplicable, has been observed in 

 some females. The lappets at the extremity of the abdomen, each 

 side of the tail, have been already described as very short in the 

 female. On their lower surface there is an irregular osseous process, 

 from which a slender corneous organ, which we suppose to be a duct, 

 runs forward and a little inward, gradually diminishing, and termi- 

 nates with a few irregular curves (fig. q). The peculiarity we refer to, 

 is an appendage to this lappet, arising from the termination of the 

 internal duct (fig. It). It is a long corneous duct, wholly external, 

 terminating in an oval sac of similar texture, and usually filled with 

 a whitish fluid. These appendages have been observed, in a few 

 instances, hanging each side of the terminal joint of the body (fig. t). 

 In one instance the ducts were crossed over the adjacent articulation, 

 and each attached by its sac to the lappet of the opposite extremity. 

 These are the only facts that have been discovered respecting these 

 singular organs. They were found attached to very few individuals, 

 and in these the eggs were scarcely developed.* 



The figures on Plate 92, representing the relations of the parts in 

 the various Caligoidea, hardly require particular remark. There is 

 much confusion in different works, with regard to the limits of the 

 thorax and abdomen, and the appendages pertaining to them. The 

 comparisons that have been made appear to settle the doubts on this 

 point. We have added Dichelestion, 6 a to 7c, from the Plates in Ed- 

 wards's Cuvier (Plate 79). We suspect that the appendages of Nico- 

 thoe, lettered e, in 1 a, of Plate 79, in Cuvier, will prove to be the 

 second antennae, on farther examination, although called maxillae by 

 Edwards, since they resemble these organs in Dichelestion ; moreover, 

 unless so related, the second antennas are here obsolete. 



The Lernaeoids have a closely parallel character, as will be seen 

 from the appendages of a Lernentoma (figs. 7 a, b, etc.), on the same 

 Plate. The prehensile legs behind evidently correspond to the simi- 

 lar organs in Ergasilus and Corycaeus — the first pair of feet in Cory- 

 caeus, or the second pair, as we name them, in the Caligidae. They 



* The Caligus Americanus afforded the preceding details, and the representation on 

 page 93. In the investigations the author was aided by Dr. C. Pickering. 



