286 DR. ARTHUR WILLEY ON 



were numbers of relatively large, bright red bodies with a 

 variable and irregular contour. These bodies were not mentioned 

 in Doflein's treatise on the Protozoa ; but were duly described by 

 F. Schiitt (' Die Peridineen der Plankton-Expedition,' i. Theil. 

 27 plates. Kiel und Leipzig, 1895). This author calls the red 

 bodies in P. divergens, hygrosomes (p. 84), and attributes their 

 formation to similarly shaped plastids, tei'med hygroplasts (p. 74). 

 He found that their contents are of a fatty nature, blackening 

 with osmic acid and dissolving in ether (p. 85). It is possible 

 that they may exhibit the property of phosphorescence, though I 

 had no opportunity of testing them for this quality. 



L. Plate i^'' Pyrodiniimi hahamense, n. g., n. sp.," Arch. Protis- 

 tenk. Bd. vii. 1906 ; see Steuer, op. cit. p. 307) suggested that the 

 phosphorescence of Pyrodiniu'ni depended upon the oxidation of 

 the numerous oil-drops at the hinder end. Biitschli mentions 

 numerous fat-drops in Peridinium divergens, which, according to 

 Pouchet, often form an annular zone parallel with the transverse 

 groove ; and this same species has been designated the luminous 

 Peridinium of the Gulf of Trieste. 



BracMolaria, the larva of Asterias, appeared in the tow from 

 August 10th, and attracted my particular attention on account of 

 the three papuliferous adhesive pi'ocesses with a median sessile 

 sucker between them, upon the preoral lobe. This Brachiolaria 

 is virtually identical with that of Asteracaoithion pallidus 

 (= Asterias vulgaris Stimps.) as figured by Alexander Agassiz 

 ('Embryology of the Starfish,' 1864; see Selections from 

 Embryological Monographs compiled by Alexander Agassiz, 

 Walter Faxon, and E. L. Mark. II. Echinodermata. Cambridge, 

 Mass., 1883). Agassiz stated that A. vidgaris reproduces only in 

 the third week of August at his more southerly station. 



Behind each of the three adhesive pi-ocesses, Avhich are called 

 " brachiolarian arms," there is a long tentacle-like process which 

 may be referred to as a bipinnarian arm. As the term implies, 

 the ciliated band is continued upon the bipinnarian arms but not 

 upon the adhesive processes. On the other hand, the hydroccel, 

 which can be traced forwards from its pore-canal, sends a diver- 

 ticulum into each of the adhesive processes but not into the 

 bipinnarian arms. 



The adhesive processes, or "brachiolarian arms," are structures 

 sui generis, but they are pai"alleled by the three adhesive processes 

 of the Ascidian larva. There is this in common, that they are 

 developed upon the preoral i-egion of the larval body ; they serve 

 for the permanent (Ascidian) or temporary (Asterias) fixation of 

 the larva, and they consist of one median dorsal process and two 

 lateral processes. It would be hard to find a closer convergence 

 (parallel adaptation) in the category of adhesive organs. Without 

 presuming that they sta.nd for anything more than physiological 

 adaptations, it seems legitimate to infer that some indirect 

 suppoi't, by way of analogy, is given to my interpi-etation of the 



