129 



be doubted that 0. dumosa Lym. and 0. rudis Lym., both known from 

 off Southern California, will be found there also. It is thus very well pos- 

 sible that the specimens from Panama comprised here under species b 

 really represent two or three different species. 



Specimens referable to the same type and hardly distinguishable from 

 the specimens from Panama were found in the Malacca Strait (30/Xl, 1899); 

 in the Gulf of Aden (14/Xl, 1899; 2— 3/V, 1900); in the Red Sea, off Jebel 

 Zukur (5/lV, 1900); in the Bay of Bengal (5° 50' N. 85° 30' E. 4/1, 1914). 



To the same larval type the larva from the Adriatic Sea, figured by 

 Job. Mtiller in his V. Abhandl. Taf.VlI. Fig.l, must further be referred. 

 In the "Echinodermenlarven d. Plankton-Exped." p. 56 I have referred 

 this larva to Ophiothrix fragilis, as is also done by Job. Miiller. It is, 

 however, more probable that it belongs to the other Ophiothrix-species 

 found in the Adriatic, viz. 0. echinata M. & Tr. The fact that in the Danish 

 seas, where only 0. fragilis occurs, only the larval type of species a has 

 been found, is not in favour of the suggestion that we may have here only 

 a variety of the 0. fragilis-larysi. If that should be proved ultimately to 

 be the case, it would be impossible to distinguish the larval types of species 

 a and b, and the 

 larva of 0. fragilis 

 and other related 

 species would turn 

 out to have an ex- 

 traordinary range 

 of variation. 



Species c. (PI. 

 XIX, Fig. 2). This 

 species has the same 

 shape as species a, 

 but differs marked- 

 ly from it in the 

 pigmentation, the 



postero-lateral 

 arms being strongly 

 pigmented (black?) 

 in their whole length, continuously, not in spots separated by unpigmented 

 parts. In the skeleton no noticeable difference appears to exist (Fig. 55 

 to compare with Fig. 53). The small difference in the shape of the trans- 

 verse rods seen in the two figures is hardly constant enough to represent 

 a vaUd specific difference. 



17 



Fig. 55. Skeleton of the Ophiopluteus of Ophiothrix, species c. =»%. 

 al. anterolateral rod; b. body rod; e. end rod; m. median process ; pd. 

 posterodorsal; pi. posterolateral; po. postoral rod ; tr. transverse rod. 



