^42 ARTHROPODA phylum vii 



Fainily 9.. Entomoconchidae. 

 Shell suh-cjlobose, more or less inequivalve ; anterior edge truncate and with central 

 Portion of nmrgin inturned so as to leave a simple or sinuate sht. Beah not developed. 

 Entomoconchus M'Coy ; Offa Jones, Kirkby and Brady. Carboniferous. 



Geological Range of the Ostracoda. 



Numerous supposed Ostracoda {Bradoria, Beyrichona, etc.) liave been described 

 from the Cambrian, biit all of these now prove to be Brancliiopods. The earliest 

 undoubted Ostracoda are indicated by a few species of Leperditia found m the 

 Beekmantown beds (Lower Ordovician) of Tennessee. Diiring the Middle and 

 Upper Ordovician these Crustaceans flourished greatly, and form excellent horizon 

 markers. The prevailing Ordovician and Sihirian types belong to the Leperditiidae 

 and Beyrichiidae, although toward the close of the Silurian numerous Cypridae make 

 their appearance. 



Devonian Ostracoda are less numerous, but manifest essentially the same types as 

 in the earlier periods. Here, however, the larger Leperditiidae are entirely wanting. 

 Although many small species of archaic genera persist in the Carboniferous, the aspect 

 of the fauna is changed by the strong development of Cypridinidae. Thereafter 

 Ostracods are but sparsely represented until the Cretaceous, when certain genera, 

 especially Gythere, develop a surprising variety of species, Little difference can be 

 detected between Tertiary Ostracods and their modern descendants, although on 

 account of the facilities for studying the anatomy of the soft parts it has been possible 

 to distingiiish many more genera among the living forms. 



[The above revision of the groups Branchiopoda and Ostracoda has been prepared by 

 Dr. R. S. Bassler.— Editor.] 



Superorder 4. OIRRIPEDIA Bur meist er. Barnacles.^ 



Sessile, mostly hermaphroditic animals, endosed in a memhranous mantle which 

 is often covered with calcareous plates. Body attached by the anterior extremity of the 



^ Literature : A. Recent Forms : — Thompson, J. V., Zoological Researches and Illustrations. 



1. Cork, 1830. — Discovery of the Metamorphosis in the Lepades, etc. Phil. Trans. Roy. Soc, pt. 



2, 1835. — Burmeister, H., Beiträge zur Naturgeschichte der Rankenfüssler. Berlin, 1834. — Martin- 

 Saint-Ange, G. J., Memoire sur l'organisation des Cirripedes. Mem. Savans Strang., Acad. Sei., 

 Paris, 1835, vol. y\.— Darwin, C, A Monograph of the Sub-Class Clrripedia. Ray Soc, 1851-54, 

 vols. i., \i.—Hoek, P. P. C, Report on the Cirripedia. Rept. Challenger Exped., ZooL, viii., x., 

 lS8Z-8i.—AtiHvülius, 0. W. S., Studien über Cirripeden. Svensk'. Vetensk. Akad. Handl., 1893, 

 vol xxvi., no. I.—Oroom, T. T., On the Early Development of the Cirripedia. Phil. Trans. Roy. 

 Soc, 1894, vol. c]xxxv.— Hansen, H. /., Phyllopoda and Cirripedia. Plankton Expedition, 1895. 

 —Oruvel, A., Monographie des Cirrhipedes. Paris, 1905. 



B. Fossil Forms.— Sowerby, J., and /. de C, The Mineral Couchology of Great Britain. 

 London, 1812-30. — Roemer, F. A. Die Versteinerungen des norddeutschen Kreidegehirges. Hanover, 

 1840-41.— Z>amm, C, A Monograph of the Fossil Lepadidae of Great Britain. Palaeont. Soc, 

 1851.— A Monograph of the Fossil Balanidae and Verrucidae of Great Britain. Ibid., 1855.— 

 Bosquet, J., Monographie des Crustaces fossiles du terrain cretace du Duche de Limbourg. Mem. 

 Commiss. Carte geol. Nederlande, 1854.— Notice sur quelques Cirripedes recemment decouverts 

 dans les terraius cretaces du Duche de Limbourg. Haarlem, 1857.— Reuss, A. E., Ueber fossile 

 Lepadiden. Sitzungsber. Akad. Wiss. Wien, 1864, vol. x\\x.—Wood%oard, IL, On Turrilepas, etc. 

 Quar. Journ. Geol. Soc, 1865, vol. xxi.— Barrande, J., Systeme Silurien du centre de la Boheme, 

 I. Siippl., lS72.—Seguenza, G., Ricerche palaeontologiche intorno di Cirripedi terziarii della Provincia 

 dl Messma, Pts. i., ii., Naples, 1873-76. Marsson, J., Die Cirripeden und Ostracoden der weissen 

 Schreibkreide der Insel iRügen. Mittheil, naturw. Ver. Neu- Vorpommern und Rügen, 1880, vol. 

 xn.~Zütel, K. A., Bemerkungen über einige fossilen Lepaditen aus dem lithographischen Schiefer 

 und der oberen Kriede. Sitzungsber. Bayer. Akad. Wiss., 1884, vol. xiv.— Faber, ö. L., Remarks 



