390 MARGARET ROBINSON. 



he considers that^ as the two hindmost have not special 

 ganglia, they are not true segments, but, rather, joints of a 

 segment ; and here he alhides to the jointing of the sixth 

 abdominal segment in Gnathophausia, which he says is 

 not accompanied by any corresponding division of the 

 ganglion. 



He regards the extra joint in Gnathophausia and the 

 two extra joints in Nebalia as being representatives of the 

 telson. In this paper he gives a schematic tree of the 

 Crustacea. In the tree the Leptostraea, the Protoschizopoda 

 and the Stomatopoda are made to come off together from the 

 Protomalacostraca. 



In 1887 Sars, in his Report on the Phyllocarida) of the 

 Challenger, following Dr. Packard (in ' Phyllopod Crustacea 

 of North America'), is inclined to derive the Nebaliadse f rom 

 copepod-like ancestors. He says that the Podophthalinia are 

 in no way related to them, but that the Branchiopoda proba- 

 bly came from the same stem, and have become altered to 

 suit conditions of life, whereas the Nebaliadse have preserved 

 many primitive features. 



In 1889 Clans published his last paper on Nebalia. In 

 this he gives a very full and detailed account of the anatomy, 

 and puts forward at some length his views as to the sys- 

 tematic position of the animal. He mentions several fresh 

 pieces of evidence in favour of its being a Malacostracan. 

 The chief of these are : 



(a) That the openings of the genital ducts in both sexes 

 are in the Malacostracan position. He had found the male 

 ducts previously. 



[h) The great complexity of the brain. 



(c) The structure of the eyes and the optic ganglion, which 

 resemble those in My sis. 



{d) The rudimentary shell gland and the eight pairs of 

 ectodermal excretory glands on the thoracic legs. These 

 function as well as the antenuary gland. 



(e) The two last abdominal segments, as representing the 

 Malacostracan telson. The last but one of these he says has 



