422 COMPARATIVE ANATOMY chap. 



J. Barrande. Systime silurien du centre de la BoMme. \o\. I. Prague, 1S52. 



Supplement. 1874. 

 J. W. Salter and H. Woodward. A Monograjjli of British Trilobites. Pakconto- 



ijraphical Society, 1867-1884. 

 Fr. Schmidt. Herision dcr ostbaltischen sihirischen Trilohiten. I. Mim. dc VAcad. 



imj}. de St. Pitershourg. Ser. YII, tome 30. 1881. 

 C. D. Walcott. The TriloMtce. Kew and old evidence relating to its organisation. 



Bull. Mils. Comp. Zoology, Cambridge, Mass. Vol. VIII. 1881. 



Gigantostraca and Hemiaspidse. 



J. Nieszkowski. Der Eurypteriis remipes aus den obersilurischen Scliiehten der 

 Insel Oesel, in Arcliiv f. Natnrgcsehiehte Liv-, Est-, und Kurlands. 1. Ser. 

 2. Band. 1869. 



H. Woodward. A Monograph of British fossil Crustacea belonging to the order 

 Mesostomata. Palaontograpihieal Society. Parts I-V. 1866-1878. 



Works of Huxley, Salter, "Woodward, Bail}', Schmidt, etc. 



Xiphosura. 



Alph. Milne-Edwards. Ledierches sur VAnotoniie des Limules, in Ann. Sciences 



naturellcs, 5" serie, t. XVII. Paris, 1873. 

 A. J. Packard. The Anatomy, Histology, and Embryology of Limulus pMlyphemus, 



in Mem. Boston Society Natural History. Boston, 1880. 

 E. Ray Lankester. Limulus an Arachnid, in Quart. Journ. Micr. Science, vol. 



21. London, 1881. 

 J. S. Klngsley. Xotcs on the Embryology of Limulus, in Quart. Journ. Micr. 



Science, vol. 25. London, 1885. 

 Treatises of J. van der Hojven, Gegenbaur, Packard, Dolirn, R. Owen, GuUand, 



etc. 



Second Appendage to the Class of the Crustacea 

 The Pantopoda (Pyenogonidse). 



The body, in comparison -(nth the long and slender limbs, is 

 extremely redu.ced, and falls into three divisions — proboscis or beak, 

 trunk, and hind -body. The ppoboscis articulates with the most 

 anterior trunk segment. At its point lies the mouth surrounded by 

 three lips, and it contains internally the greater part of the fore-gut 

 (" iish trap " apparatus). It consists of three pieces lying side by side 

 longitudinally, an up)per median piece and two lower lateral pieces. 

 The trunk consists of 6 segments, the three anterior of which are 

 always fused together ; it has lateral outgTOwths on to the ends of 

 which the limbs are hinged. The hind-body is unsegmented, short, 

 truncated, and devoid of limbs. 



Extremities. — 7 pairs of extremities occur tj^pically. The first 

 extremities (1), the cheliceraj, are innervated from the brain, and in 

 the young animal end in pincers ; in the adult they are often reduced 

 or altogether wanting. The following extremities (2-7) are inner- 

 vated from the ganglia of the ventral chord, 2 and 3 from the most 

 anterior ganglion, which consists in the larva of two separate ganglia. 



