66 



The relationship of the Mediterninean forms, viz., Tlicodisca 

 anserina, and Th. liriostouui to the South African is un- 

 certain, but the latter (7. liriosfoiiia) comes very near it. 

 Kinberg* records another species {A. dendriticiiui) from 

 Vancouver. 



The Anthostoma robiistiiiii of Verrillf seems to have a very- 

 similar structure, and the same may be said of the Aricia 

 Icevigaia (Grube) of De St. Joseph,^ from the Mediterranean. 

 The species described by Treadwell || from the Antilles are very 

 similar, as also is the Aricici setosa of Verrill,§ from Flatts bilet 

 beach, Bermuda — in shell-sand at low tide. In the latter form 

 the branchii« also begin on the sixth setigerous segment and 

 continue nearly to the end of the body. 



A small form about 5 or 6 mm. in length presents certain 

 differences from the foregoing. 



Head forming a small blunt cone — larger in proportion than 

 in the adult. 



Body very little tapered in front — more distinctly diminished 

 towards the tail — where it ends in 4 short cirri (Plate V., fig. 28.) 



Each segment has similar appendages to those of the adult, 

 viz., an inner ciliated branchial process, a dorsal lamella with 

 the tuft of tapering finely serrated longer bristles, a conical 

 ventral lobe with a few spines, the tips of which have an f-shaped 

 curv'e, and a group of shorter serrated bristles as in the adult. 

 The f-shape of the tips of two of the spines is noteworthy at 

 this stage. 



The presence of 4 short subulate anal cirri — two dorsal and 

 two ventral, if this be the same species (and it appears to be) is 

 therefore a feature of moment, and shows that a change occurs 

 during the development of the anal cup. At this stage, there- 

 fore, if the above interpretation is right, the posterior end 

 agrees with that of Tlicodisca as described by ClaparedelF and 

 Cunningham and Ramage,** but Claparede does not mention 

 bilid bristles or hooks, whereas Cunningham and Ramage do, so 

 that it is dcubtful if the latter pertains to the same genus. At 

 any rate the young form alluded to in the foregoing sentences 

 agrees with the Tlicodisca of Claparede ; and in all probability 

 the adults have the same appendages. 



* Olvfi^. K. Vetensk-Akad. Fork. iS60. No. g, p. 337. 

 t Op. cit. p. 597, PI. xiv., fii;. 76. 



X Ann. Sc. Nat. 8e., Ser. v., p. 360., I'l. wi, 1". 168-175. 

 II Bullet. U.S. Fish Com. lyoo, p. 203. 

 § Trans. Conn. Acad, x., p. 651. ic;oo. 



* Glanurcs Zoolom. p. 44, PI. iv., iigf), and .Vnn. Chcl. Xap. p. 310. Pl.x.\iv.,fig. 3. 

 ** Trans. K.S.E., vol. xxxiii., p. 642, PL xl., tig. 8. 



