PLATE XXVII. 



Strongylocentrotus Drdbachiensis, 1 - J^. 



1. Interior of test, section of test across the equator, a, auricles ; j, soft part of jaw ; 



m, muscles supportinj,' pyramid ; i , oesophagus ; i", part of intestine attached to 

 broad fiat mesentery ; i, abactinal loop of intestine across ambulacra ; i'", i'^"-, loops 

 of intestine, nearer anal extremity, filled with pellets ready to be cast out ; '?, actinal 

 loop of intestine. 



2. Interior of abactinal part of test, showing the ovaries, o, o', and origin of stone canal ; 



«, a", a", anibulacral plates ; ia, ia", iuterambulacral plates ; z" z" , z" a'", porif- 

 erous zones. 



3. Interior of abactinal part of test, showing position of intestine and ovaries ; o, o', o", 



o'", o"'-, o', ovaries ; % , part of intestine leading to anal opening ; i", one of the 

 loops of the digestive canal. 



4. The abactinal part of the test removed. (/, genital ring ; o, o , o" , o"\ ovaries ; 



i, i", i", loops of intestine. 



Diadema setosum, .5. 



5. Showing course of intestine, abactinal part of test removed, a, auricles ; m, m, muscles 



of attachment of pyramid to the auricles ; c, c , bracket supporting muscles extending 

 to auricles ; i", oesophagus attached to flat mesentery : i, i' , i'", flat folds of intestine. 



Echinanthus rosaceus, G. 



6. Interior of part of test showing one of the petals, g g, genital ring with tubes leading 



to ovaries, o, o ; a , median ambulacral space ; 2, inner edge of poriferous zone ; 

 a", ambulacral pores beyond petal ; a'", row of pores of petals. 



{All Figs, natural size except 6, which is tioo thirds natural size.) 



The Drawings are made from preparations by A. AGASSIZ and N. BOWDITCH. 



