760 



ARTHROPODA 



PHYLUM VII 



following pairs are usually chelate. The gills are typically in several series attached 

 to the bases of the thoracic limbs and to the lateral wall of the thorax. 



Although undoubted Decapods have not been recognised in formations 

 earlier than the Trias, it is probable that some of the caridoid forms known 

 from the Carboniferous may be the forerunners of this large and varied order. 



Pig. 1474. 



Penaeus meyeri Oppel. Upper Jura (Litliograpliic Stone) ; 

 Solenhofen. 1/2. 



Suborder A. NATANTIA Boas. 



Body usually compressed, rostrum compressed and serrated. First somite of 

 abdomen not much smaller than the others. Legs slender, sometimes with evopodites ; 

 any one of the first three pairs may he enlarged. Abdominal appendages well developed, 

 used for swimming. 



Of the three tribes which compose this suborder, the Penaeidea and Stenopidea 

 agree in having the first three pairs of legs chelate (with a few exceptions in the 

 Penaeidea), and the side-plates of the second abdominal somite not expanded ; they 



differ in that the third pair of 

 legs is much larger than the 

 first in the Stenopidea, but not 

 in the Penaeidea. The Caridea 

 never have the third pair of 

 legs chelate, and have the 

 side -plates of the second ab- 

 dominal somite expanded to 

 overlap those of the somites 

 in front and beliind. 



The Penaeidea are some- 

 what doubtfully represented 

 in the Trias, but a long series of fossils from the Solenhofen Lithographic Stone can 

 be referred with certainty to this tribe. Some of these are included in the Recent 

 genus Penaeus Fabricius (Fig. 1474), while Acanthochirus Oppel, Bylg'ia, Drobna and 

 Dusa Miinster are extinct genera. 



The Stenopidea comprise a small number of Recent forms which show some 



Bull. Soc. Geol. France, 1859, ser. 2, vol. xvi. — Fritsch, A., Uber die Caliauassen der bdhmischeu 

 Kreide. Abhandl. Bolim. Ges. Wiss., 1868, vol. liv. — Knebel, W. von. Die Eryonjden des oberen 

 Weissen Jura von Siiddeutsclilaud. Arch. Biontol., 1907, vol. ii. — Lijrenthey, E., Uber die Brachy- 

 iiren der paliiont. Sanimlung des Bayer. Staates Termeszet Filzetek, Budapest, 1898, vol. xxi. — 

 Idem, Beitriige zur Decapodenfauna des ungarischen Tertiiii-s. Math.-naturw. Ber. aus Ungarn, 

 1898, 1903, vols, xiv., xviii. — Idem, Falaontol. Studien Uber tertiiiren Decapoden. Op. cit., 1907, 

 vol. xxi. — Idem, Beitriige zur tertiaren Decapodenfauna Sai-diuiens nnd Agyptens. Op. cit., 1908, 

 1909, vols, xxiv., XXV. — Mark, W. von der, Fossile Fische, Krebse und Pflanzen aus der Kreide. 

 Palaeontogr., 1863, vol. xi. — Idem, and Schluter, C, Neue Fische und Krebse aus der Kreide von 

 Westphalen. Op. cit., 1868, vol. xv. — Meyer, H. von, Neue Gattungen fossiler Krebse. Stuttgart, 

 1840. — Moericke, W., Die Crustaceen der Stramberger Schichten. Palaeontogr., 1897, Supplem. 

 vol. ii. — Oppel, A., Ueber jurassische Crustaceen. Palaeont. Mittheil. Mus. Bayer. Staates, 1862, 

 vol. ii. — Ortmann, A. E., On Limiparus in the Upper Cretaceous of Dakota. Anier. Journ. Sci., 

 1897, ser. 4, vol. iv. — Pilshry, H. A., Crustacea of the Cretaceous formation of New Jersey. 

 Proc. Acad. Nat. Sci. Pliilad., 1901, vol. iii. — Hathbnn, M. J., Descriptions of fossil crabs from 

 California. Proc. U.S. Nat. Mus., 1908, vol. xxxv. — Schluter, C, Die Macruren-Decapoden 

 Westphalens. Zeitsclir. Deutsch. Geol. Ges., 1862. vol. xiv. — Idem, Kreide- und Tertiiir-Krebse des 

 nordlichen Deutschlands. Op. cit., 1879, vol. xxxi. — Idem, Podocrates im Senon von 

 Braunschweig. Op. cit., 1899, vol. Ii. — Stimpson, IT. , Fossil Crab from Gay Head. Journ. 

 Boston Soc. Nat. Hist., 1863, vol. vii. — Tribolet, M., Descriptions des cru.stacees dii terrain 

 neocomien. Bull. Soc. Geol. France, 1874-75, ser. 3, vols, ii., iii. — Mliitfield, B. P., American 

 si3ec\es oi' Iloploparia. Bull. Anier. Mus. Nat. Hist., 1907, vol. xxiii. — Winkler, T. C, Etudes sur 

 les genres Peinphix, Glyj}haeu, etc. Arch. Mus. Teyler, 1883, ser. 2, vol. \. — Woodward, H., 

 Macrurous Crustacea, etc. Quart. Journ. Geol. Soc, 1872-76, vols, xxix., xxxii. 



