176 



quite possible that other speeies may have a PUiteus-larva, eorresponding 

 to the fact shown in this work that within llie genus Aslcrina some s|)ecies 

 have a typical Bipinnaria-larva, while others have a shortened, direct 

 development as in the classical case of Asterina gibbosa. — 



The larva of Ophionereis squamulosa belongs to the same type as that 

 of Ophioderma brevispina, described by Caswell (irave. There are some 

 minor dilTerences in the shape of these two larv<e, that of Ophionereis squa- 

 mulosa having the anterior lobe distinctly longer than that of Ophioderma 

 brevispina. Also the arrangement of the vibratile bands is somewhat dif- 

 ferent, especially the posterior band, as a comparison of Fl. XXXI, Fig. 3 

 with PI. Ill, Fig. 22 of Grave's Memoir will make evident. 



The statement of Grave (Op. cit. p. 83) that the usual Pluteus skeleton 

 is formed in the larva of Ophioderma brevispina, while there is no trace 

 of a larval skeleton in Ophionereis squamulosa, would appear to indicate 

 a very im{)ortant dilTerence between these two larvse. Later on, however. 

 Grave has announced^) that he mistook the beginning skeletal plates of 

 the Ophiurid for the larval skeleton. There is thus no larval skeleton in 

 the- larva of Ophioderma brevispina either. 



A larva closely resembling that of 0. brevispina was taken pelagically 

 atTaboga, Gulf of Panama, 18/XI. 1915. Probably it belongs to one of the 

 Panamic species of Ophioderma. It would seem superlluous to give a closer 

 description or figures of it. — To the same larval type belongs that describ- 

 ed by Joh. Miiller^) from Triest under the designation ■wurmformige 

 Asterienlarve", and also those described from Madeira by Krohn^). It 

 may perhaps be suggested that the Mediterranean foim belongs to Ophio- 

 derma longicauda. 



In the "Echinodermenlarven d. Plankton-Exped." I designated also 

 these worm-shaped larvae as Ophiopluteus. Hamann*) objects to this 

 designation, because there is neither a ciliated band nor a larval skeleton 

 in these larvte, not to mention that the usual larval arms are totally lacking. 

 I would, however, still tliink it justifiable to use this designation. In the 

 larva of Ophiura af finis'), Ophiopluteus Metsehnikoffi and 0. Claparedei we 

 have difTerent stages of the reduction of the typical Pluteus-shape. From 



') Caswell Grave. On the occurrence among lu'hinodcrms of larva: with cilia arranged 

 in transverse rings; with a suggestion as to their significance. Biol. Bull. V. 190:i. p. 178. 



*) Joh. Muller. Cber die Larven u. die Metamorphose d. Hololhuricn u. .\sterien. 

 III. Abhandlung. Abh. d. Akad. Berlin. 1850. p. 26. Taf. VI. 8^12. VII. 1 — 1. 



^) A. Kroiin. L'ber einen neuen Enlwicklungsmodus d. Ophiuren. Miiller's .\rchiv. 

 1857. p. 369, 373. Taf. XIV. B. Fig. 1 — }. 



Th. Morlensen. Ecliinodermeniarven d. Plankton-Exp. p. 65 — 66. 



*) O. Hamann. Die Schlangensterne. Bronn. Klassen u. Ordn. III. 1901. p. 860. 



*) Th. Mortensen. Notes on the development and the larval forms of some Scandinavian 

 Echinoderms. p. 133. 



