THE CRUSTACEA 



B 



a. 



laid the foundations of classification. The order Branchiopoda, as 



first defined by Latreille in 

 1817, included Ostracoda, Cope- 

 poda, and Limulus ; and Milne- 

 Edwards, in 1840, while exclud- 

 ing these, retains the later added 

 Nebalia. Later attempts to 

 extend the limits of the group 

 to readmit the Ostracoda and 

 Branchiura have not met with 

 support, while Claus's demon- 

 stration of the Malacostracan 

 affinities of Nebalia and its 

 allies is now generally accepted. 

 Among the authors who, in the 

 first half of the nineteenth 

 century, contributed to a know- 

 ledge of the group, Jurine, 

 Fischer, and Baird may be 

 mentioned. Zaddach's mono- 

 graph on Apus is still the chief 

 source of information on many 

 points of anatomy. Leydig's 

 work on the Cladocera is especi- 

 ally important as regards internal 

 anatomy and histology; and 

 Weismann's series of papers 

 deal, among many other points, 

 with the remarkable phenomena 

 of their reproduction, which had 

 attracted attention from the 

 time of Schaffer. As is the case 



p r .__ 



with most other groups of Crus- 

 FIG. 15. tacea, modern conceptions of 



the morphology of the Branchio- 

 poda are largely indebted to 

 the works of Glaus. Lankester's 

 containing the "uterus" paper on the appendages and 



the front of the head 



nervous system of Apus greatly 

 influenced opinion in favour of 

 the primitive position of the 



Kra.nchinec.ta paludosa, one of the Anostraca 

 x 4. (After Sars.) A, female ; , male, a', 

 antennules ; a", antennae, enlarged in the male 

 to form clasping organs ; p, paired penes of 

 the male ; ut, ventral prolongation of the genital 

 segment in the femal< 



filled: with eggs. O: _. 



between the antennules, is the unpaired eye, 

 and,. just behind it, the stalked compound 



Dorsal to the pear-shaped mandible is seei. 



groove which appears to divide the head-region 

 into two segments. Following this, the trunk 



... vv ... uv^.uv,!* vo. A \jiiirvriiig I'll in, l/Ut; II'UIIK --j * . , 



shows eleven limb-bearing and eight limbless -tjrancniopoda. Among the more 



MOmit.ps Sntiuirlac f It A +olo*-vn\ + 1*.! *;., 4- .,.i ..,. __ i _ A 



somites (besides the telson), the first and second 

 of the latter partly coalesced. 



_ 



purely descriptive and faunistic 

 works the numerous papers of 

 G. O. Sars hold an important place, and mention may also be 

 made of the fine monograph on the Cladocera of Sweden, published 



