jt>8 TACK sKor.snKnr, 



I. It iiiiii. liwii;. Till' mature .sj)t'citin'i\s witc assumed to licloii^ In ..Stajic I", the three hirvae 

 to the hist hirval stajjie, ., Stage 111". Tlie reason whv the mature specimens were assumed to 

 belong to , .Stage T* was obviousU- the rehitively ^reat diflerence with regard to the length of 

 the shells hetween these specimens and ..Stage 111"; these two stages were really prosuniably 

 soparatoil 1)\' an intermediate stage. Tiie (picslKm tlien becomes: did tlir (hree larvae reall\- 

 belong to tlie last larval stage? Unfortunately the statements given are too incomplete for me 

 to venture to say anything cjuite definite in this matter. It seems to me, however, from pi. XIX, 

 tig. 77. very probable that these tliree specimens belonged to the next to the last larval stage. 

 If this is the case, then the reason for assuming a mature stage between the stages found by 

 G. H. Fowler also disappears. On the other hand (i. H. FoWLliH found in this material two 

 stages of mature females, , .Stage I" being represented by seventeen specimens, ,, Stage, 11" 

 by only three. Were both these stages mature? For the same reasons as in the case of the males 

 it is very diffii'ult for me to make any statement on this point, but it seems to me practically 

 ([uite certain that the three specimens of ,, Stage 11" were not mature; pi. XIX, fig. 80 definitely 

 shows this. They were probably larvae in the last stage. If this is the case, there was in this 

 sex too only one mature stage. 



\Miat has been said above will be sufficient to show clearly how uncertain is the basis 

 on which G. H. FOWLEH has constructed his important hypothesis. 

 D,(^s,on of //,,.. _^j. jg gppj^ above, p. 564. this group was divided by G. VV. MClleh, 1906 a, into two sub- 



families: Thauinalocyprinae and Cunchoecinae. The same classification is also used in tlie 

 present treatise. Of these two sub-families Thaiimatocyprinae, which is so interesting from 

 a systematic point of view, was unfoitunately, however, quite unrepresented in the collections 

 investigated by me. 



Sub-Family Conchoecinae. 



Sub-Fam. Conchoecinae, G. W. MCllki;, 1906 a, p. 43. 



Description: — Shell: — This is dimorphous, but in a number of cases only rather shghtly 

 so. — • The rostral incisur is shallow in all species, but it never seems to be quite absent. An apparent 

 deepening of the incisur occurs, however, in all the forms so far known. This deepening has arisen 

 because the outer lamella of the shell curved out like a pocket just above the incisur, forming a 

 rostrum which is in most cases rather extensive (this rostrum is thus not homologous with the part 

 with the same name in the Cypridiniformes); the original anterior margin of the shell continues 

 (as G. W. MiJLLER pointed out as early as 1894, p. loi) in the shape of a more or less S-shaped 

 ctirved Une (..Buchtlinie", according to C. Claus's terminology) proximally on the inside, or 

 perhaps more correctly speaking, on the ventral side of the rostrum. The rostral incisur is always 

 situated above half the height of the shell, in most cases quite near its dorsal margin 



