CERIANTIIAKIA. ^, 



43 



As is known (Busch 1S51), the larval form of Cniuuthiis iiiniihrat/accus appears not to have a 

 long period of development, but to sink quickly to the bottom. It may also be possible, therefore, that 

 the most Iar\al forms of the Cerianthidae famil\ are not planktonic for an\- long period, and that llie 

 larval forms, which are more adapted for the plaukt(jnic mode of life, belong principally to the families 

 Acoutiferidae and Botrucnidiferidae. 



Besides the generic characters given above, there are imdoubtedly a number of others that 

 will prove to be of significance for the discrimination of genera. In the above however I have endeav- 

 oured to give the genera as extensive a range as possible in order not to run the risk of liaving 

 to suppress certain characters afterwards. However as these more secondary characters may be of use 

 for a future characterisation of the genera, they are stated here. 



Genus Pacliyccriaiifluis: vSpecies as a rule with rather numerous mesenteries. Breadth of sipho- 

 nogh'ph and length of Inposulci vary. The median streak with a tendenc}- at least to break up into 

 two streaks. The mesogloeal processes of the ciliated tracts issue from the main lamella of the 

 mei^entery. Mesenterial threads (craspedonemes) and bunches of the ciliated tracts may or ma_\- not 

 be found. The region of the craspedion may or may not be found. The cuido-glandular tract on 

 mesenteries M and in sometimes threadlike, from its exterior suggestive of the "acontia" and of the 

 craspedonemes of the ciliated tract. 



Genus Ccriaiiflius: Species as a rule with numerous me.senteries. Siphonoglyph narrow. Hypo- 

 snlcus as a rule small. The median streak and mesogloeal processes of the ciliated tracts as with 

 Pacliyccriautliits. Mesenterial threads (craspedonemes) and bunches in the region of the ciliated tracts 

 ma)' or may not be found. The region of the craspedion may or ma\- not be found. 



Genus Ccriaiithcopsis: Species with numerous mesenteries. Siphonoglyph narrow. Hyposulcus 

 small. Median streak with marked tendency to divide into two lateral portions. The mesogloeal 

 processes of the ciliated tracts issue from the main lamella of the mesenter>'. Craspedonemes and 

 bunches in the region of the ciliated tracts occur. The region of the crasjDedion is present, long. Proto- 

 cnemes 2 and the longest metacnemes with a crasjDedoneme from the most aboral part of the region 

 of the craspedion. 



Genus Aracliiiaitfluis: Sj^ecies with a small number of mesenteries. The 2nd couple of proto- 

 cnemes without cnido-glandular tract region. Number of metamesenteries not large. Very broad si- 

 phonoglyph and long hyposulcus. With distinct filament region on hyposulcus. Median streak divided 

 up into 2 streaks sharply marked off. The mesogloeal processes that support the ciliated tracts issue 

 from the mesogloeal folds of the median streak. The region of the craspedia on M and m well 

 developed. Without mesenterial threads (craspedoueme.s) and bunches in the region of the ciliated tracts. 



G&nus, Bofniciiidift-r: Species with a small number of mesenteries. Siphonoglyph narrow, feeble 

 hyposulcus. Median streak simple, not subdivided. The mesogloeal processes of the ciliated tracts 

 issue from the main lamella of the mesenter\-. Long craspedion region. Mesenterial threads (craspe- 

 donemes) and bunches in the region of the ciliated tracts not developed. 



Gtnus Bofniaiit/itis: Species with very numerous mesenteries. Siphonoglyph very broad. Hypo- 

 sulcus of medium development. Conformation of the median streak? Mesenterial threads (cra.spe- 

 donemes) occur. Craspedion region? 



