464 Prof. K. Grobben on the Genealogy and 



sharp demarcation between thorax and abdomen, this sepa- 

 ration of the two regions of the bodj cannot be utilized as a 

 froof of a closer affinity between the two forms referred to. 

 n the possession of appendages upon six of the abdominal 

 segments Xebah'a exhibits more primitive conditions than 

 Branchijyus, in which the abdomen is devoid of limbs. The 

 special development of the second antenna, as well as of the 

 oral appendages of Branchipus, and the agreement of the 

 latter organs with those of the rest of the Euphyllopods 

 would, since this is undoubtedly likewise a case of secondary 

 transformations of appendages which were originally differently 

 constituted, not have much weight in this comparison with 

 Xebah'a, where in these respects much more primitive condi- 

 tions are to be met with. 



While considering all the circumstances which have been 

 indicated, we shall still find ourselves continually reverting to 

 Branchipus in our search for a connexion with Xehalia among 

 the existing Euphyllopods. The supposition that in the 

 Branchipus type we may actually recognize an Archiphyllopod 

 remnant, from which the Malacostraca have arisen, will, as 

 containing much probability, find a further support in a sub- 

 sequent consideration. 



Into the relationships of the different groups of Malacostraca 

 I need not enter further. A genealogical tree, which best 

 exhibits the affinity of the Malacostraca, has been set up by 

 Claus *, and the reader may be recommended to consult it. 

 I would merely suggest that the origin of the lateral branch 

 for the Stomatopoda as represented in it should be moved 

 somewhat higher up, and indeed that it should not be sought 

 for until the Arch ischizo pods are reached, from which, in my 

 opinion, the Stomatopoda have developed as a separate off- 

 shoot. Above all, the youngest Stomatopod larva {Erich- 

 thoidina), which was described by Claus t, exhibits such 

 manifold relations to the Schizopods that the view which I 

 have expressed appears to be thereby confirmed. 



While on this subject I would nevertheless refer to a pecu- 

 liarity of the Stomatopods, as opposed to all other ^lalacostraca 

 with the exception of Xebalia, which has not hitherto been 

 sufficiently appreciated. This is the rostral plate, which 

 app)ears in various shapes, and is jointed to the anterior margin 

 of the cephalo-thoracic shield. The structure in question 

 reminds us of the cephalic valve of Xebalia ^ with which it is 



• C. Claus, ' Xeue Beitrage rnr >Iorphologie der Crostaoeen,' p. 104. 



+ C. Claus, *• Die Metomorphoee der SquiJliden " : Abhandlungen der 

 konigL Gesellschaft der Wissenschaften zu GottiDgen, itL Bd. 1871, 

 Tat L tig 1. 



