GENERAL REMARKS ON THE MORPHOLOGY OF THE 



PHYLLOCARIDA. 



The views of zoologists as to the systematic position of the genus Nebalia, the only 

 hitherto known recent form of this group, have been widely different. Leach, the founder 

 of the genus, placed it among the Macrura, and was followed in this view by several 

 other authors, as Lamarck, Bosc, and Desmarest, whereas Milne-Edwards in his important 

 work on the Crustacea put the genus among the PhyUopoda, placing it together with 

 the genus Apus in his family Apusidse. The great authority of the last named eminerit 

 naturalist seemed to have finally settled the question about the systematic position of 

 Nebalia, it being by the general consent of carcinologists regarded as a true Phyllopod, 

 though it was afterwards found necessary to remove it from the genus Apus, and to 

 establish a distinct family, Nebaliadse, for its reception. More recently, however, the 

 phyllopodous nature of this form has been denied by several naturalists. Thus, Dr. E. 

 Metschnikoflf, in studying the development of Nehalia, was led to the result, that this 

 form should more properly be referred to the Decapoda than to the PhyUopoda, and 

 accordingly named it a " phyllopodiform Decapod." A similar view seems also to have 

 been partly adopted by Professor Claus in transferring Nebalia from the Entomostraca 

 to the Malacostraca. Finally, the late Dr. v. Willemoes Suhm, in describing a new form 

 from the Challenger Expedition, places the family Nebaliidai among the Schizopoda. 

 Mr. Salter^ was the first to point out the apparent affinity of the recent genus Nehalia, 

 to certain Palaeozoic fossils, and Claus also recognised the relationship of Nebalia to 

 these old forms of Crustacea. In 1879 Dr. A. Packard established a distinct order, 

 Phyllocarida, for the reception of Nebalia, together with the above mentioned fossil 

 forms, which formerly had generally been regarded as true PhyUopoda most nearly 

 related to the genus Apus; and in the following year Professor Claus in the third edition 

 of his Zoology likewise referred the genus Nebalia to a distinct order, Leptostraea, 

 removing it far from the PhyUopoda and placing it among the Malacostraca. 



As to my own views, I fully agree with the above named authors, that the genus 

 Nebalia ought to be removed from the" PhyUopoda, but I am not prepared to agree 

 wdth Professor Claus in transferring it to the Malacostraca, and still less can I entertain the 



• On Peltocaris, a New Genus of Silurian Crustacea, Quart. Journ. Geol. Soc. Lond., vol. xix., 1863. 



