Shidies (111 iiiariiic ()str;irii(ls 191 



The fact that, in .spite of this, (I. \V. Mui.Li;i; cliose this coui-se is due, as is shown hv 

 the quotation given above, partly to \\\v imonipleteness, uncertainty and undoulitcd incor- 

 rectness of several of the characters included in the diagnosis of the genus (Jypridinodes given 

 by G. S. Brady, partly perhaps, above all, to the strange form Monopia flaveola described by 

 C. Glaus, 1873. 



G. W. MULLEu's criticism of (J. S. BHAltv's tliagnosis ol the genus Cypridinodes is 

 undoubtedly (juite justified. From this, however, it by no means follows tliat we are justified 

 in including the three species mentioned above in the genus Cypridina (sensu Mi'i>Li:i!l)! 



In several respects — such as the type of the shell, the sixth and seventli limbs, the 

 furca and the upper lip — Monopia flaveola agrees so strikingly witli the three species 

 mentioned that there can scarcely be any doubt of the existence of a real relationship. 



Under these circumstances is it not most convenient to follow G. W. Muller's 

 indication, quoted above, that, in the case of an eventual breaking-out of Cypridina 

 asymnietrica, C. Bairdi and V. favus we should unite these forms with Monopia flaveola 

 into one genus, Monopia'i 



I think this is true only with an important restriction. Although Monopia 

 flaveola — as is mentioned above — shows in several resjjects rather far-reaching agreement 

 with the three species in question, yet it differs from them in several characters 

 of such importance that it seems to me quite correct to distinguish it as a representative of a 

 special higher classificatory unit. Thus this form is characterized by a frontal organ of a type 

 that is very different from other known species, by rudimentary lateral eyes (these are certainly 

 represented by a pair of rather short, short-stalked, somewhat T-shaped appendages, fixed 

 near the base of the first antenna; these appendages have been interpreted by C. Clais, curiously 

 enough and certainly incorrectly, as gills (see 1873, p. 225); and G. W. Muller (1890, p. 224) 

 considered them to be remains of the gills of the primitive C y p r i d i n i d s!) and especially 

 by the slight modification of the maxilla. Contrary to the maxilla in Cypridina asymtnetrica, 

 C. Bairdi and C. favus, but similar to the same organ in all the other representatives of the 

 group Cypridiniformes hitherto known, the maxilla in Monopia flaveola has immoveable 

 endites on the protopodite and an eudopodite of fairly moderate length. On account of 

 this limb this species may be said in a way to occupy an intermediate position between 

 the three above-mentioned divergent forms and other species included in the genus Cypridina 

 (sensu G. W. MUlleri). 



For these reasons it seems to me best to retain both Monopia and Cypridinodes. I con- 

 sider them, however, as sub-genera of the same genus, Monopia. — The former sub-genus is at present 

 only represented by a single species, M. flaveola; in the latter ?ixemc\\\AedCyprMina asymnietrica, 

 C. Bairdi and C. (-- Cypridinodes) favus; in addition, as is seen below, I have described an- 

 other species of the latter sub-genus, Monopia (Cypridinodes) acuminata, a form that in its whole 

 organization shows a very striking resemblance to the representative of this sub-genus described by 

 G. W. MUller. — With regard to the distinguishing characters of these two sub-genera I merely 

 refer here to C. Claus, 1873 and to the diagnosis of the sub-genus Cypridinodes that is given 

 later on in this work. 



