42 ANNELIDA POLYCHAETA. 



gives no figures or detailed descriptions of bristles or bran- 

 chiae , I believe our specimens are referable to this species. 

 It seems to me very probable that A. antillensis , accurately 

 described by Lütken, may be identical with A. cristata] 

 that the former species has a wider geographical distribu- 

 tion is already stated by Ehlers (Florida-Annelida, p. 173) 

 who mentions it from the coast of Florida. Lütken seems 

 not to have known Stimpson's description, at least he does 

 not mention it His A. antillensis is characterized in the follo- 

 wing manner: »anuulis setigeris 17, anterioribus 6 ebran- 

 chiis , ceteris branchiferis , branchiis e foliis plumiformibus 

 c. 15 compositis, fasciculis filorum respiratoriorum ad latera 

 trunci mediaui collocatis plumassingulas formantibus; annu- 

 lis caudalibus 8 nudis (sine setis et branchiis), papilliferis. 



Longitudo usque ad 0.35 M. Hab. ad oras Ins. An- 

 tillarum." 



There is only one character in Liitken's description, 

 that is open to doubt; this is the presence of long, projec- 

 ting papillae at the ventral side of the caudal region , 

 which are identified by Levinsen with branchial filaments. 

 Ehlers, however, makes no mention of those papillae. 



Two other small specimens of Arenicola are to be men- 

 tioned , which agree with this species in the number of 

 setigerous and branchiferous segments, but which present 

 some other different characters ; therefore I am somewhat 

 dubious if they should be considered either as immature 

 specimens of A. cristata or as another species The largest 

 specimen has only a length of 60 m.m. , its caudal region 

 measuring about 12 m.m. The branchiae consist of 10 to 

 12 branchial leafs, not connected at their base; they are 

 not so slender as those of the larger foregoiug specimens, 

 their inferior filaments being more branched and longer as 

 those of the tip. The dorsal bristles are not so hairy and 

 resemble those of A. marina (fig. 11). The proboscis is 

 densely covered with acute, conical papillae; only at the 

 base there is a region of about 5 series of obtuse trian- 

 gular papillae. 



Notes from the Leyden Museum , Vol. XI. 



