282 



Family Adeonidae Busk'. 



The zixvcia, llie entire frontal suirace of which is provided with a Frequently 

 slrongly eolourod covering inemhrane, are always without spines, exlreniely Ihick- 

 walled and slrongly calcified. There are generally pores, and (he partition walls 

 are provided with numerous (in the distal half of the zou'cium usually 14 — 16), 

 small, uni])()rous roselte-plates disposed in a single row, which on account of the 

 thickness of the walls appear at the end of long canals, and the pores ap])ear in 

 a similar way. Owing to the continued deposition of calcareous matter a second- 

 ary, .sometimes even a tertiary, aperture is always present. This is more or less 

 dilTerent from the primary one, which has most often a sinus or a concave proxi- 

 mal margin. The operculum is generally well marked oil" from the covering mem- 

 brane. Aviciildiiit are hardly wanting in any species and occur in most species 

 both as dependent and independent. They are always without a calcified trans- 

 verse bar between the opercular and the subopercular area, and at lis base the 

 mandible has on either side a strongly protruding muscular process, (hrcia are 

 wanting, but gonozoircia appear in most species. The latter are somewhat larger 

 than the ordinary zoa^cia, from which they further dilTer by possessing a broader 

 aperture and l)y being generally better provided with pores. The colonies are 

 usually free, two-layered, sometimes laminate, sometimes branched, more rarely 

 incrusting. 



This extremely natural and sharply delimited family was founded by Husk 

 in his report on the Unjozoa of the (Challenger Expedition. Hut just as the author 

 did not succeed in comprehending this family in all its extent, overlooking as 

 he did, that his ^MiicroneUu' puriformis, set up in the same work, also belongs 

 to it, so also is his diagnosis of the family very incomplete, as of real, general, 

 positive characters he mentions only one, viz. the above-mentioned peculiarity 

 in the avicularian mandible, which however according to Waters'^ may also be 

 found in members of other families. On the other hand, Waters^ has pointed 

 out that the median pore which according to Busk is found in all nnMnhers of 

 tliis family can not be regarded as a family character, as this pore in some spe- 

 cies leads into the zoaH'ial cavity itself (Adeoiut, Adconellopsis), while in others it 

 leads into the space between the primary and the secondary aperture {AdconeUa). 



This incomplete diagnosis of the family may be one of the reasons for tlie 

 fact, that in .spite of its naturalness this family has not been adopted by a single 



• 8, p. 177. - lUOa, p. 777. " UKI, p. 283. 



