648 ARTHROPODA SUB-KINGDOM vn 



Cambrian evolution was very rapid, and during the Ordovician they nourished as 

 greatly as at any subsequent period. The prevailing Ordovician and Silurian 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 Cyprinidae. Thereafter but a 

 meagre representation of Ostracods is met with until the Cretaceous, when certain 

 genera, especially Cythere, develop a surprising variety and wealth of species. Little 

 difference can be detected between Tertiary Ostracods and their modern descendants. 



[The above generic diagnoses of Ostracoda have been abridged from a more extended dis- 

 cussion of the group, prepared for this work by Mr. E. 0. Ulrich, of Newport, Kentucky. 

 TRANS.] 



Super-Order 4. CIRRIPEDIA. Barnacles. Latreille. 1 



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

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

 head ; obscurely, and at times not at all segmented ; posterior portion with at most 

 six pairs of divided legs or cirri, which, however, may be fewer in number or altogether 

 absent. 



The typical and best known Cirripedes (Balanidae and Lepadidae) differ so 

 widely from all other Crustacea in their external form, solid calcareous shells, 

 slightly developed respiratory and sensory organs, and especially in their 

 hermaphroditic sexual apparatus, that until 1830 they were commonly classed 

 with the Mollusca. About this time J. V. Thompson and Burmeister showed 



1 Literature : A. Recent Forms. 



Thompson, J. V., Zoological Researches and Illustrations. I. Cork, 1830. Discovery of the 

 Metamorphosis in the Lepades, etc. (Phil. Trans. Roy. Soc., Pt. 2), 1835.Burmeister, H., Beitrage 

 zur Naturgeschichte der Rankenfiissler. Berlin, 1834. Martin- Saint- Ange, G. J., Memoire sur 

 1'organisation des Cirripedes (Mem. Savans. ]trang. Acad. Sci. Paris, VI.), 1835. Darwin, C., 

 A Monograph of the Sub-Class Cirripedia (Ray Soc., I., II.), 1851-54. Hoek, P. P. C., Report on 

 the Cirripedia (Kept. Challenger Exped., Zool., VIII. , X.), 1883-84. A urwillius, C. W. S., Studien 

 iiber Cirripeden (K. Svensk. Vetensk. Akad. Handl., XXVI., No. 7), 1893. Groom, T. T., On the 

 Early Development of the Cirripedia (Phil. Trans. Roy. Soc., 185), 1894. Hansen, H. J., Phyllopoda 

 and Cirripedia. Plankton Expedition, 1895. 



B. Fossil Forms. 



Sowerby, J., and J. de C., The Mineral Conchology of Great Britain. London, 1812-30. 

 Roemer, F. A., Die Versteinerungen des norddeutschen Kreidegebirges. Hanover, 1840-41. 

 Darwin, 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.), 1854. Bosquet, J., 

 Monographic des Crustaces fossiles du terrain cretace du Duche de Limbourg (Mem. Commiss. Carte 

 geol. Nederlande), 1854. Notice sur quelques Cirripedes recemment decouverts dans les terrains 

 cretace du Duche de Limbourg. Haarlem, 1857. Reuss, A. E., Ueber fossile Lepadiden 

 (Sitzungsber. Akad. Wiss. Wien., XLIX.), 1864. Woodward, H., On Turrilepas, etc. (Quar. Journ. 

 Geol. Soc., XXI. ), 1865. Barrande, J., Systeme Silurien du centre de la Boheme., I. Suppl. 1872. 

 Seguenza, G., Ricerche palaeontologiche intorno di Cirripedi terziarii della Provincia di Messina, 

 Pts. I., II. Naples, 1873-76. Marsson, J., Die Cirripeden und Ostracoden der weissen Schreib- 

 kreide der Insel Riigen (Mittheil. naturw. Ver. Neu-Vorpommern und Riigen, XII.), 1880. Zittel, 

 K. A., Bemerkungen iiber einige fossilen Lepaditen aus dem lithographischen Schiefer und der oberen 

 Kreide (Sitzungsber. Bayer. Akad. Wiss., XIV.), 1884. Faber, C. L., Remarks on some Fossils of the 

 Cincinnati Group (Journ. Cincin. Soc. Nat. ScL, IX.), 1887. Hall, J., and Clarke, J. M., Palaeon- 

 tology of New York, VII. p. 209, 1888. Clarke, J. M., Notes on certain Fossil Barnacles (Amer. 

 Geol., XVII.), 1896. Matthew, G. F., On occurrence of Cirripeds in the Cambrian (Trans. N. Y. 

 Acad. Sci., XV.), 1896. Logan, W. N., Cirripeds from Cretaceous of Kansas (Kansas Univ. Quar., 

 VI.), 1897. 



