MELLITA LONGIFISSA. 535 



analogue of the hexapora type ; differs, as far as the few specimens existing 

 show, from the Panama species in the size of the lunules, which are longer, 

 more as in M. hexapora, while the position of the apex is intermediate be- 

 tween the two. The outline in profile is regularly conical ; the tuberculation 

 is large but distant; the petals are small, of uniform length, with very broad 

 poriferous zones, broader than in either of the American species. The lo- 

 cality of these specimens is said to be undoubted. The material existing is 

 not in a sufficiently good state of preservation to discriminate the three 

 hexaporous species of this genus more accurately. 



Red Sea? 



Mellita longifissa 



! Mellita longifissa Mich., 1858, Rev. Mag. Zool., No. 8. 



Pl.XI.f. 24-27. 



This species is readily distinguished from its Atlantic representative (M. 

 testudinata) by its long and narrow lunules ; the posterior interambulacral 

 lunule is especially developed. The anterior extremity is quite rounded ; 

 edge of test thin ; the posterior extremity truncated. The development of 

 the petals is very unequal ; the posterior pair are long, arched, much as in 

 some species of Encope, with an extremely narrow interporiferous space ; 

 the anterior pair are short, making a more decided angle with the general 

 trend of the median ambulacral line than in M. testudinata. The apex is 

 more anterior, and the apical system comparatively smaller, than in M. tes- 

 tudinata. The odd anterior petal is somewhat longer than the anterior 

 pair, with a wider interporiferous space, much as in petals of M. testudinata. 

 There is no special difference on the actinal side, as regards the general ap- 

 pearance of the ambulacral furrows ; the interambulacral spaces are broader 

 proportionally than in the Atlantic species, and their general tuberculation 

 slightly larger and more uniform in size. The mouth, owing to the extreme 

 length of the posterior lunule, is very eccentric anteriorly, the anus being 

 placed nearly in the centre of the actinal side. 



Panama ; Gulf of California. 



