4<^o r- 



The first pair of legs is short, but the second makes up by its inordinate 

 length and slenderness ; while the three hinder pairs are more nearly equal in size, 

 and are known as " anchoral " feet, since it is by them that the creature attaches 

 itself firmly to the object on which it rests. 



All the feet are provided with sharp claws, which fold back upon the preced- 

 ing joint ; but in the last three pairs this joint is furnished with a sharp spine, 

 against which the claw sliuts. Thus our Ca;;/-e//a, secured by six anchors, can ride 

 safely in spite of waves and currents, its long body swaying to and fro, and its 

 forelegs busy in catching its prey. The Caprella. appear to be parasitic on 

 hydroids and sponges. 



The species of which I append a technical description was dredged iil about 

 eight fathoms of water, from a bottom of mud and weeds, in Hakodadi Bay, 

 Japan, by W. J. Fisher, naturalist of the Tascai-om. Mr. Fisher has present- 

 ed two specimens, male and female, to this Academy. 



I believe the species to be new, although it is just possible that it may have 

 been previously described by some naturalist whose works do not grace the 

 shelves of our Academy. I have named it C.spinosa. The male somewhat re- 

 sembles the C. ntfenuata of Dana, the chief dilFereuces being the spines upon 

 the five posterior segments, and the absence of the spine upon the head. 



The females diifer so greatly from the males in the comparative lengths of the 

 several joints of the body and antennte, that I was at first inclined to believe 

 they belonged to another species ; but since the two form^ were always dredged 

 in company, and the specimens of one form are all males, while those of the 

 other are all females, it is evident that they are the two sexes of the same 

 species. 



Caprclla spiaosa. Lockington. 



Male. Body very slender ; segments elongate, second thoracic segment more 

 than one-half longer than the first, and very slender. No spine on dorsal sur- 

 face of head. Superior anteunaj longer than half the body; first joint little 

 piore than half the length of second ; third joint nearly as long as second ; 

 flagellum rathe longer than basal joint. Inferior antennae reaching to about 

 the first third of the second joint of the superior antenna?. Hand of second pair 

 of legs very narrow, with three teeth on the underside, one a short distance be- 

 hind the claw, a second close to the first, and a third posterior to the middle. 

 The third and fourth segments have a sharp spine on each side, above the bran- 

 chia; and near the hinder margin, and the three posterior segments are furnished 

 with similar spines. 



Length of body, 1 11-16 inch. Length of superior antenna?, about 1 inch. 



Female. Body less elongated than in the male ; third and fourth segments 

 swollen at the sides, and both these segments armed with a long, sharp spine, 

 the point curving towards the head ; fifth and sixth segments armed with a 

 straight spine. Second pair of legs about as long as the second segment of 

 the body, the basal joint armed with a sharp spine on the upper side of distal 

 end ; hand shorter than basal joint, with a single acute tooth on the posterior 



