440 Prof. K. Grobben on the Genealogy and 



LXXII. — A Contrihution to the Knowledge of the Genealogy 

 and Classification of the Crustacea. By Prof. Karl 

 Grobben, of Vienna*. 



A CONSTANT attraction towards fresii consideration in respect 

 of phylogeny is exerted by the Crustacea, a class presenting 

 a variety of form and withal sharply defined, and which in 

 Fritz Muller's treatise ' Fiir Darwin ' (Leipzig, 1864), which 

 has become famous, first served as a test of the correctness of 

 the Darwinian theory. It was to such a consideration that I 

 subjected the group on the basis of ideas which I have pur- 

 sued for a number of years. 



As the starting-point for my reflections I availed myself of 

 the striking fact, as to which doubts have been expressed in 

 isolated cases only f, that the large Phyllopods, which I shall 

 henceforth designate as Euphyllopoda, and which among 

 existing Crustacea come nearest to the ancestral forms of 

 which they may be regarded as remnants, are represented by 

 three types. These are Branchipiis, Apus, and Estheria, 

 which, while agreeing in all essential structural characters, 

 differ very widely one from another in outward appearance as 

 a whole, as well as in the special form of the several parts of 

 their bodies. 



On the other hand, it struck me that among the Euphyllo- 

 poda certain points of agreement with the Malacostraca are 

 especially exhibited by Branchipus, while the type of which 



* Translated from the ' Sitzungsberichte der kaiserlichen Akademie 

 der Wissenschaften. — Mathematisch-naturwissenschaftlicbe Classe,' ci. Bd. 

 ii. Heft, Jahrg. 1892, Abth. i. pp. 237-274 : Wien, 1892. 



t Thus it is considered by A. S. Packard that the large Pl;}]lopodsare 

 a highly developed and extremely specialized bi'anch of the Cladoceran 

 stem, which is further connected by means of the Ostracods "with the 

 Copepods, from which it must be held to have been derived (' A Mono- 

 graph of the North-American Phyllopod Crustacea,' United States Geolo- 

 gical and Geographical Survey, "Washington, 1883, pp. 417, 419, and 

 448). 



Moreover, G. O. Sars (' Report on the Phyllocarida collected by H.M.S. 

 * Challenger ' during the years 1873-76,' Zoology, vol. xix., 1887) regards 

 the Copepods as the most primitive of recent Crustacea, and derives the 

 Brancliiopods from Copepod-like ancestors. In a similar manner IJartog 

 ("The Morphology of Cyclops and the Relations of the Copepoda," 

 Trans. Linn. Soc. Lond. ser. ii. Zoology, vol. v., 1888) considers the 

 Copepods to be a primitive type and the ancestral form of tJie Crustacea. 

 It was not until a later stage in the series that, according to Hartog, the 

 Protophyllopods were derived I'rom a Copepod-like ancestral form of this 

 kind ; the Protophyllopods on their part gave rise on the one hand to the 

 Phyllopods, and on the other, through the Nebaliids, to the Arthrostraca 

 and Thoracostraca. 



