THE CRUSTACEA 27 



larval form, corresponding perhaps (as Hatschek suggests) to the 

 stages immediately succeeding the trochophore in the development 

 of Annelids, but with some of the later -acquired Crustacean 

 characters superposed upon it. 



The five sub-classes into which the Crustacea are divided in the 

 classification here adopted appear to represent independent or 

 nearly independent lines of descent from the primitive stock. 

 Their relations to each other and the probable course of evolution 

 Avithin each group will be dealt with in subsequent chapters. 



It may be mentioned that the classification introduced by 

 Latreille in 1806, in which the Malacostraca are opposed to all 

 the other Crustacea grouped together under the name of 

 Entomostraca, is still frequently adopted. The Entomostraca, 

 however, like the Invertebrata, constitute a very heterogeneous 

 group, defined only by negative characters and having no claim 

 to retention in a natural system of classification. 



LiTERATUIlE. 



[Selection of important works dealing with the Class as a whole.) 



In this list and in those appended to the foUowinci; chapters no attempt has 

 been made to give a complete bibliography of the suVyect. The references given 

 in the works mentioned will, however, provide tlie necessary gnidance for the 

 student who desires a further acquaintance witli the vast mass of carcinological 

 literature. 



1. Brunt-:, L. Contribution :i I'etude do I'exerction chez les Arthropodes. Arch. 



Biol. XX pp. 217-422, pis. vii.-ix., 1903. 



2. Claus, C. Untersuchungen zur Erforschung der genealogischen Grundlage 



des Crustaceensystems. 4to. Wien, 1876. 



3. Xeue Beitriige zur Morphologic der Crustaceen. Arb. zool. Inst. 



Wien, vi. pp. 1-108, pis. i.-vii., 1886. 



4. Das Medianauge der Crustaceen. Arb. zool. Inst. Wien, ix. pp. 225- 



266, 4 pis., 1891. 



5. Dana, J. D. The Crustacea of the United States Exploring Expedition, 



1838-1842. 2 vols. 4to, and Atlas, fol. Philadelphia, 1852-1853. 



6. Dohrn, A. Geschichte des Krebsstammes. Jenaische Zeitschrift, yi. j.p. 



96-156, 1871. 



7. Gerstaecker, A., and Ortmann, A. E. Crustacea, in Bronn's Klassen und 



Ordnungen des Thierreichs, Bd. v. Iste Abth. 1320 pp. 50 pis., 1866- 

 1879, by Gerstaecker. 2te Abth. viii + 1319 pp. 128 pis., 1881-1901, by 

 Gerstaecker-to p. 1056, continued by Ortmann. 



8. Grohhen, C. Die Antennendriise der Crustaceen. Arb. zool. Inst. Wien, ui. 



pp. 93-110, pi. ix., 1881. 



9. Zur Kenntniss des Stammbaumes und des Systems der Crustaceen. 



Sitz.-Ber. Akad. Wien, ci. Abth. i. pp. 237-274, 1892. Translated in 

 Ann. Mag. Xat. Hist. (6) xi. pp. 440-473, 1893. 



