123 



HARDWICKE'S SCIENCE-GOSSIP. 



[June 1, 1869. 



species owes its name to the conformation of the 

 right antenna of the male — Labidocera, from Xaj3ig, 

 forceps, and Ktpag, a horn — with the Latin adjective 

 magna, in virtue of its great size. These are a 

 species of the genus Calanus, of the order 

 Lophyropoda. When fully developed, each antenna 

 in either sex consists of twenty-five segments ; of 

 these the first thirteen present nothing remarkable, 

 but all the remaining segments in the right antenna 

 of the male enter into the composition of the 

 remarkable prehensile organ depicted below. 



Fig. 91. Hinge-joints of right antenna of male Labidocera magna, x 250. 



"This organ is composed in the following manner: 

 the fourteenth and four following segments are 

 dilated into a large flask-like organ, the neck of 

 which is eked out by the nineteenth and twentieth ; 

 the next two segments are fused together, and are 

 articulated with the foregoing by a simple joint, 

 and the whole of the remaining segments form 

 another piece similarly articulated with the 

 intermediate piece ; so that the whole results in 

 two simple joints, susceptible of flexion in one 

 direction only. Two processes of the same nature, 

 but differently placed, and more elongated, lie side 

 by side upon the fore part of the first compound 

 segment. This piece and that which succeeds it 

 act upon each other like a pair of jaws, each 

 furnished with an array of sharp conical teeth, 

 while the last compound member of the series plays 

 over the upper surface of the eighteenth segment." 



(Dr. McDonald, E.R.S., in Mag. Nat. Hist., 

 1S53.) 



The fifth pair of legs also differ in the sexes, the 

 right leg of the fifth pair of the male forming a 

 powerful prehensile apparatus. 



These formidable instruments look more like 

 engines of war from the armoury of Mars, than 

 snares and lures from the repository of Cupid. 

 They certainly meet with very hard knocks some- 

 where, for in innumerable specimens subjected to 

 the microscope, the grappling antennae were found 

 broken at the hinge, the two ter- 

 minal articulations having been 

 torn off, whether in mortal com- 

 bat with a rival knight jousting a 

 Voutrance for possession of the 

 queen of beauty, or by the indig- 

 nant struggles of some surpass- 

 ingly chaste Vestal of the Deep, I 

 cannot determine. 



It has been my fate to speak 

 of the universal distribution of 

 parasites, in a previous number. 

 " The intestinal canal of animals," 

 says Leidy, "is most frequently 

 infested by entoparasites on ac- 

 count of the ease with which 

 their germs enter into the food. 

 Aquatic animals are more troubled 

 by Entozoa than those which arc 

 terrestrial, because the water 

 affords a better medium of access 

 than the air;" and our Labid- 

 ocera forms no exception to this 

 rule. Having opened his thorax 

 for the purpose of examining his 

 internal economy under the micro- 

 scope, a low power detected a tiny 

 object apparently on the move : 

 the quarter-inch and B eyepiece 

 showed it to be an Entozoon, 

 wholly unlike anything I have ever seen or heard of 

 anywhere. 



Fig. 95. Entozoon from the thorax of Labidocera magna, 

 x 450. 



The body (<?), which is here shown swinging away 

 to the left, is sack-like and cylindrical, having 

 somewhat the appearance of a bladder slightly 



