126 



lo llu' yoiinj> ()|)liiiiri(l, being cast ofT when melninoi|)hosis is coniplclcd. 

 (CoiniK above, |). 121). 



riu' study of the numerous larvie ot Ophinlhrix (or ol loiiiis belonging 

 at least to llic laniily Opliiolhi idiidir) which I havi' lioni dilTerent locai- 

 ilies: Japan, the Piiilippines, Malacca Slrail, the (iulf of Aden, the (iulf 

 of Panama, ('alifornia, the West Indies and the Kuiopean Seas makes 

 evident the interesting fact, that it is simply i m possible to find reliable 

 characters by which to distinguish with certainty the vari- 

 ous species of these larvie. There are some exceptions. The forms 

 described here as species c and d, especitdly the latter, are fairly well 

 characterized and easily distinguished; but the forms designated as species 

 a and b certainly both comprise several species, as is evident from the 

 fact that they are found in widely separated localities (luirope. West 

 Indies, Panama, .lapan), which have no s[)ecies of Opiiiothrichida' in com- 

 mon. If specimens of these larv;e from (he (hITeri'id localities were put 

 togelhei'. it would be impossible to se|)aiate the dilTerenl species again. 

 Perhaps the |)igmentaliou of the hnva- may proxc to be somewhat dif- 

 ferent, so that it would be possible to distinguisii the species on having 

 the living specimens. Hut the pigmentation is liable to be more or less 

 destroyed on jireservalion. In the skeleton no reliable distinguishing cha- 

 racters can be pointed out. There may be some slight dilTerences in the 

 length and thickness of the body rods and in I he length of the median 

 processes; but 1 iiave been unable to find any delinite specific characters 

 therein. In consecpience of this fact 1 have thought it useless to give a 

 descri|)tion of each of these larval species, which can only from zoogeo- 

 graphical facts be recognized as separate species. 



Species a. (PI. XIX, Fig. 1). The posterolateral aims are about three 

 times the length of the inner arms and generally have three large spots 

 of black pigment; some smaller pigment spots aie found in the posterior 

 part of the body. The skeleton, see I^'ig. 5.'). 



To this type belongs the larva of Ophiulliiix JKUjilis. Specimens not 

 distinguishable from this larva were fouiui at Misaki, .fapan (the species 

 represented in PI. XIX, Fig. 1); in the Malacca Strait (oil Pulo Pisang, 

 1/XII, 1899); oir the l<:ast end of Sokotra (XII, 191.H); Taboga, Panama 

 (XII, 1915); San Diego, California (7/IX, 1915); St. Cruz, West Indies 

 (l(i/VI,1915, Il.Faye). Likewise the Ophiopluleus /oftu.s/u.s (Fchinodermen- 

 Larven d. Plankton-Mxped. p. 57. Taf. V. Fig. 3 — 1) from Fernando Xo- 

 ronha belongs to this type.^) 



') III tlic pUici- (|uole<l I slaled lliat tliLs larva is iiihIouI)Ii<II> iicaily rclalcd lo I ho Ophiu- 

 thrix-larva, then adding: "zu welcher Ophiure sie gehort kaiiii man iiiclil crkcniu'ii"; tlie 



