742 ARTHEOPODA phylum vii 



Family 9. Entomoconchidae. 



Shell sub-globose, more or less inequivalve ; anterior edge truncate and with central 

 portion of margin inturned so as to leave a simple or sinuate slit. Beak not developed. 



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



Geological Range of the Ostracoda. 



Numerous supposed Ostracoda (Bradoria, Beyrichona, etc.) have been described 

 from the Cambrian, but all of these now prove to be Brancliioi^ods. The earliest 

 undoubted Ostracoda are indicated by a few species of Leperclitia found in the 

 Beekniantown beds (Lower Ordovician) of Tennessee. During the Middle and 

 Upj)er Ordovician these Crustaceans flourished greatly, and form excellent horizon 

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

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

 their apjjearance. 



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 sj)arsely represented until the Cretaceous, when certain genera, 

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

 detected between Tertiary Ostracods aud their modern descendants, although on 

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

 to distinguish 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. OIKRIFEDIA Burmeister. Barnacles.^ 



Sessile, mostly hermaphroditic animals, enclosed in a membranous mantle which 

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



1 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. — Burineistcr, H., Beitriige zur Naturgeschichte der Raukenfiissler. Berlin, 1834. — Martin- 

 Saint-Ange, G. J., Memoire sur I'organisation des Cirripedes. Mem. Savans llltrang., Acad. Sci., 

 Paris, 1835, vol. vi. — ■Daricin, C, A Monograph of the Sub-Class Cirripedia. Ray Soc, 1851-54, 

 vols, i., ii. — lloek, P. P. C, Report on the Cirripedia. Rept. Challenger Exped., Zool., viii., x., 

 1883-84. — Anrivillius, G. W. »S'., Stndien iiber Cirripeden. Svensk. Vetensk. Akad. Handl. . 1893, 

 vol. xxvi., no. 7. — Groom, T. T., On the Early Develoi)ment of the Cirripedia. Phil. Trans. Roy. 

 Soc, 1894, vol. clxxxv. — Hansen, H. J., Phyllopoda and Cirripedia. Plankton Expedition, 1895. 

 — Gruvel, A., Monographic des Cirrhipedes. Paris, 1905. 



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

 London, 1812-30. — Roemer, F. A. Die Versteineruugen des uorddeutscheu Kreidegebirges. Hanover, 

 1840-41. — Darwin, C, A Monogi\iph of the Fossil Lepadidae of Great Britain. Palaeont. Soc, 

 1851. — A Monograph of the Fossil Balauidae aud Verrucidae of Great Britain. Ibid., 1855. — 

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

 Comraiss. Carte geol. Nederlande, 1854. — Notice sur quelques Cirripedes recemment deconverts 

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

 Lepadiden. Sitzungsber. Akad. Wiss. Wien, 1864, vol. xlix. — Woodward, H., On Turrilepas, etc 

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

 I. Suppl., 1872. — Segnenza, G., Ricerche palaeoutologiche intorno di Cirripedi terziarii della Pi-oviucia 

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

 Schreibkreide der Insel iRtigen. Mittheil. naturw. "Ver. Neu-Vorpommeru und Riigen, 1880, vol. 

 xii. — Zittel, K. A., Bemerkungen iiber eiuige fossilcn Lepaditen aus deni lithographischen Schiefer 

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



