«0 



TAGK SKOGSBRRC. 



Ptirca. 



Frontal organ. 



Other organs. 



The larval stages. 



wlu'tluT those folds arc arnuigocl segiueutally or imt). Ki. Miller, 1870, p. 273, had already 

 I'xpressod this view; as did C. Cl.\US also, 1876, p. 96. As a proof of the probability of this 

 assuinptiim it mav be pointed out that weak transverse, folds have been observed on the 

 ilorsid sitle of the back of the body iu the males of a number ol species belonging to other genera 

 of C y p r i d i n i d s; cf., for instance, Cypriilina dursuserrata (J. W. MOLler, 1908, pi. IV, 

 Hg. 2. In the male of Cyprulina Hilgendorfi G. W. MtlLLBR, 1890, we find at the corresponding 

 place gills in the form of comparatively high transverse folds, seven in niiiuliii-; as in the 

 last-nieutioued species but contrary to the genus Asterope, these folds extend across tlie back 

 without any median break; only the foremost one has a medial concavity. G. W. MOl.LKR, 

 1890. p. 224. homologizes these gills with those of the genus Asterope, supporting his view 

 especially by theii' number and position. It is, at any rate, certainly premature at the present 

 time to describe these gills by the terra „epipodial appendages" . 



Furca: — 



With regard to this organ the terminology used by G. W. MU1.LER has been adopted 

 in this work. Consequently the furcal claws are counted distally-proximally, contrary to the 

 practice of a number of other writers, e. g. G. S. Brady. This method is necessitated partly 

 because in several forms these claws vary in number, when it is always the small proximal claws 

 that are subject to variation, and partly because they are formed ontogenetically distally- 

 proximally, the proximal ones not appearing until the matui-e stage is reached. 



Frontal organ*: — 



This is most frequently termed in the present work ,,the rod-shaped organ", on 

 account of its shape. 



^^'ith regard to other organs the terminology used by G. VV. MtJLLER has been 

 adopted in this work. 



Terminology of the larval stages: — 



By Stage I in the present work is meant the oldest larval stage, the stage next to 

 the mature stage. The stage immediately preceding Stage I is called Stage II, the stage 

 immediately preceding Stage II is Stage III, and so on. 



This terminolog}' has not been used by previous writers. C. Claus and G. W. MOLLER 

 denote the youngest freely Uving larval stage by Stage I, the subsequent stage by Stage II, 

 and so on. This terminology seems inconvenient on account of the deficiency of our present 

 knowledge of the post-embryonal development of this group, especially with regard to the 

 youngest larval stages. A consequence of the employment of this terminology has been that 

 larval stages with the same numbers do not correspond to each other in the works of different 

 writers or even in different works of the same writer. Thus Stage I of the genus Conchoecia 

 in G. W. MuLLER's works of 1893 and 1894 — of which this author says, 1893, p. 376, „Das 

 erste mir bekannt gewordene Stadium, das ich geneigt bin, fiir das erste iiberhaupt zu halten" 

 — corresponds to Stage III of the same genus in C. Claus, 1893. 



* Contrary to the practice ia G. W. Muller's works, in tiiis treatise, as in VV. Giesbrecht, 1913, the nauplius 

 eye is not reckoned as a frontal organ (W. Giesbrecht, 1913, p. 120). G. W. Mli.i.er wriles. 1912. p. 8: ..Das Frontal- 

 organ . . . besteht aus clem dreiteiligen Medianauge iind . . . ." 



