154 ECHINODERMS OF THE BRITISH ISLES 



5. A short recurrent rod present ; transverse rods directed obliquely 



forwards (Fig. 88, 3) . . . . Amphiura filiformis 



No recurrent rod ; transverse rods straight (Fig. 87, 4) 



OphiopluteiLs dubius Mrtsn. 



6. Postero -lateral rod fenestrated (Fig. 129) . Ophiura texturata 

 Postero -lateral rod simple, not fenestrated ... 7 



7. A pair of ciliated lobes at the base of the postero -lateral arms ; 



one or two inwardly directed processes at the point of the end 



rods (Fig. 87,1;88,2) . . . Ophiocomina nigra 



No ciliated lobes, no inwardly-directed processes at the point 



of the end rods ........ 8 



Fig. 88. — 1-4. Various species of Ophiuroid larvae (Ophiopluteus). 5-6. The 

 posterior part of the body-skeleton in two species of Ophiviroid larvje. 



1. Ophiothnrfragilis(xSO). 2. Ophiocomina tiigra {\ca. 45). 3. Amphiura filiformis 

 ( X ca. 50). 4. Ophiura albida ( x ca. 50). 5. Ophiopholis aculeata ( x 100). G. Ophio- 

 pluteus compressus ( x 100), e, End rod ; fl, Ciliated lobes ; k, Body rod ; pr. Median rod ; 

 t. Transverse rod. In 2 the two ciliated lobes on the dorsal side are, unnaturally, extended 

 backwards ; on the living larva they are all directed horizontally outward. 



8. Transverse rods without forwardly- directed processes or median 

 rods .......... 9 



Transverse rods with 1-2 forwardly-directed processes or median 

 rods .......... 10 



- 9. All the arms broad and flattened ; transverse rods obliquely 

 upwardly-directed, simple (Fig. 88, 4) . . Ophiura albida 



Arms narrow ; transverse rods flattened, somewhat widened 

 and irregularly indented (Fig. 88, 6) 



Ophiopluteus compressus ]\Irtsn. 



10. One median rod ; postero -lateral arms very long, directed nearly 



horizontally (Fig. 87, 3; 88, 1) . . Ophiothrix fragilis 



Tw^o median rods ; postero -lateral arms of medium length, not 



directed nearly horizontally (Fig. 88, 5) Ophiopholis acideata 



