SUPER-ORDER v M A LACOSTRACA 



Order 1. PHYLLOCARIDA. Packard. (I, Cl.uis.) 



Body composed of jive cephalic, <'i<jl<t ////<///*/>, a ml /</ / ,;,//,/ //////////;/ .*></// 



and thorax covered //// </ /A/// i-hitinous or partially calcified carapace, u-li> 

 may be in a single piece or divided into separate valves by a striiiylit, unart /minted, 

 single or double hinge. In front of the carapace is a narrow movable plate or /.<//////' . 

 The head bears two pairs of antennae, ami tnlh-<l compound < rack segments 



with soft phyllopodifoi'm legs. Abdomen composed of annular ft 

 ends in a spinifoi'm caudal plate (telson) provided with lateral spines. 



The recent genus Nebalia (Fig. 1370) is regarded by Packard and Glaus 

 as the surviving representative of ancient Crustacean types, very numerous 

 during the Palaeozoic, which had been previously classed with the Phyttopotln, 

 but more properly form a distinct group (Phyllocaridd) connecting the 

 Entomostraca with the Malacostraca. The genus is very generalised, combining 

 Copepod, Phyllopod, and Decapod-like features with other more fundamental 

 characters of its own. Upon it is based largely the definition of the order, 

 but some of the extinct families show structural differences from the living 

 type which will eventually require their removal from this association. 



Cephalic appendages have not been satisfactorily determined in any fossil 

 species, although traces of them have been noticed in a few genera (Cryptozoe, 

 Oeratiocaris, Ehinocaris). In the absence of contrary evidence there is every 

 reason to suppose that the appendages of the head, thorax, and abdomen were 

 on the type of Nebalia, since there is such close correspondence in the form of 

 carapace, rostrum, and abdomen. Owing to the non-preservation of limbs, 

 distinctions within the group are based principally on variations in the 

 structure of the carapace, and in the number of body segments. Several 

 fossil genera (Echinocaris, Rhinocaris, Mesothyra) bear a distinct optic node or 

 pit, suggesting a sessile simple eye in contradistinction to the stalked faceted 

 eye of Nebalia. In these genera, also, large cuspidate masticatory organs 

 have been found, which were apparently attached only by means of muscles ; 



1 Literature: 



Salter, J. W., On some new Fossil Crustacea, etc. (Quar. Jotirn. Geol. Soc., XII. p. 26, XIX. \,. 

 75), 1856-62. On New Silurian Crustacea (Ann. Mag. Nat. Hist., V. p. 153), I860. Hall, J., 

 Palaeontology of New York, III., 1859. 16th Ann. Kept. N.Y. State Cabinet Nat. Hist. 1863. 

 Woodward, H., On a new Genus of Phyllopodous Crustacea (Quar. Jouni. Geol. Soc., XXII. 

 p. 503), 1866. Geol. Mag., IX. pp. 433, 563, 1872 ; IX. pp. 386, 444, 1882 ; II. pp. 345, 

 385, 460, 1885. Clans, C., Ueber den Bau und die systematische Stellung von Nebalia (Zeitschr. 

 wissensch. Zool., XXII.), 1872. Barrande, ./., Systeme Silurien du centre de la Boherae, I. 

 Suppl. 1872. Whitfield, R. P., Notice of new Forms of Fossil Crustacea, etc. (Amer. Jouru. Sci. 

 [3], XIX.), 1880. Clarke, J. M., New Phyllopod Crustacea from the Devonian (Amer. Journ. Sci. 

 [3], XXIIL), 1882. New Discoveries in Devonian Crustacea (ibid. XXV.), 1883. Ueber deutsche 

 oberdevonische Crustaceen (Neues Jahrb., I. p. 178), 1884. On the Structure of the Carapace in 

 Rliinocaris, etc. (Amer. Nat., XXVII. p. 793), 1893. 14th Kept. State Geol. N.Y. I., 1898. 

 Packard, A. S., A Monograph of the Phyllopod Crustacea of North America (12th Ann. Kept. U.S. 

 Geogr. Geol. Surv. Terr.), 1883. Beecher, C. K, Ceratiocaridae from the Upper Devonian Measures 

 (2nd Geol. Surv. Penn. Kept. PPP), 1884. Jones, T. R.,&nd Woodward, H., Various Papers in Geol. 

 Mag., I.-X., 1884-94, and Reports 1-12 of Comm. on Fossil Phyllopoda Brit. Assoc. Adv. S.-i.. 1883- 

 95. Novak, 0., Remarques sur le genre Aristozoe (Sitzungsber. bolmi. Akad. Wissensch. p. 239) 

 1885. (Ibid. p. 674), 1886. On Occurrence of a New Form of Discinocaris in Bohemia (Geol. Mag. 

 [3], IX. p. 148), 1892. Sars, O. 0., Report on the Phyllocarida (Leptostraca) Rept. Challenger 

 Expedition, XIX., 1887. Hall, J. and Clarke, J. M., Palaeontology of New York, VII., 1888. 

 Whitjield, R. P., New Genus of Phyllocaridae (Bull. Amer. Mus. Nat. Hist., VIII.), 1896. -Jones, 

 T. R., and Woodward, H., Monograph of the British Palaeozoic Phyllopoda (Phyllocarida, Packard), 

 Part III. (Palaeontogr. Soc.), 1898. 



