310 



GOMPARATIVE ANATOMY 



C H AP. 



the 3 other joints together with the flagellum to the endopodite, and the scale 

 to the exopodite, of a typical biramose limb. This is clear from the fact that the 2d 

 antenna; of the Malacostramn larvfe {Nauplius, Protozocea) show the typical biramose 

 structure, the exopodite (which is often still jointed) being transformed in the course 

 of development into the squame of the antenna in the adult. The 3 distal joints of 

 the shaft are thus only the 3 proximal joints of the endopodite enlarged. 



Arthrostraca.— ^mi)/w>orfa, the squame (exopodite) is wanting. In the female 

 Sypcridce. the antenna; are rudimentary. Isopoda, squame wanting. In Bopijridce 

 and Entonisddce the antenna; rudimentary. Anisopoda, squame present in Apseiides. 



Fig. 210.— Second or posterior antenna of various Crustaceans. A, lolanthe acanthonotus, 

 lioimd (after Beildard). B, Eulinmadia texana, larva (after Packard). C, Cyclops signatus 

 (after TJljanin). D, Pseudocalanus elongatus (after Brady). E, Trebius oaudatus, parasitic 

 Copepod (after Kroyer). F, Enlimnadia Agassizil, adult Phyllopod (after Packard). G-I, 

 Eupliausla pellucida (after Sars). G, Last FurclUa stage ; H, first Cyrtopia stage ; J, young Euph- 

 avsia. K, Astacns fluvlatills (after Huxley) ; rjo, aperture of the green gland (antennal gland) ; 

 ej, exopodite (squame) ; en, endopodite with flagellum ; I, proximal ; II, distal joint of the proto- 

 podite. 



Thoracostraca. — Cumacea, antennse witliout squame, in the male with unusu- 

 ally long flagellum, in the female rudimentary. Stomatopoda, with large squame. 

 Schizopoda, with well- developed squame (Fig. 210, G-T). Deeapoda, except the 

 Brachyura, with squame (Fig. 210, K), tlie outer being the posterior antennae. 



The antennal glands which have been observed both in the Entoinostraca and the 

 ilalacosiraca show a constant relation to the 2d antemiEe. Tliat is to say, they 

 always open on the basal joint of their protopodites. 



c. The Mandibles (Fig. 211). 



The mandibles correspond -with the 3d pair of extremities (the 2d 

 pair of biramose feet) of the Nauplius. They lie to the front at 

 the side of the mouth and serve for mastication. They are origin- 



