from Juj>an and the Indian Ocean. 91 



(' Ingolf ' Ecli. pi. xii. fii^s. 2, 3). The spicules arc ralluT 

 Rm;ill, ine,milar, fenestrate plates, arranged in tlie lower part 

 ot the tulio-foot in two distinet series; there is no siickini;- 

 disk and no prolonp;ations from the spicules into the partition- 

 wall of the foot (/Vi. bursan'tiin). The abactinal tube-feet 

 are almost quite destitute of spicules. 



The primary abactinal spines, both ambulacral and inter- 

 ambulacral, are very characteristic (PI. V. fi;^s. lo, IG). In 

 the lower part they are quite smooth ; some way out several 

 spread thorns appear, and these soon become arran-red in very 

 distinct and rather distant whorls, the part between the 

 whorls being quite smooth. All tliese spines unfortunately 

 are broken, so that it is impossible to give any idea of their 

 length or of the structure of the point. The spines are 

 straight. These spines afford the most prominent character 

 ot the species. In P/i. bursarnun the primary abactinal spines 

 are curved and smooth, in placenta straight and smooth. 

 The secondary spines (PI. V. tig. 17) are thorny in their 

 whole length, but tlie thorns are not arranged in whorls. 

 The spines of the aetinal side are like those of the other 

 species. 



The shape of the test is the same as in placenta, but it is 

 more delicate and fragile than in that species. The specimens 

 before me are bleached, only the skin-bag of the primary 

 aetinal spines is faintly violet. 



'1 his species is evidently nearly related to Ph. placenta and 

 hursdtium^ whereas Ph. allemans, de Meij\Me, on account of 

 the different arrangement of the tubercles and its pedicelhiriai 

 being provided with a keel, stands more apart. De Meiiere 

 ('JSilioga' Ech. p. 32) says respecting this species: — " Es 

 scheint mir eine kleine Erweiterung der beziiglichen Dia'^nosa 

 [ot the genus Phonnoaoiun'] meiir erwunscht, als dass ich fiir 

 diese Art gleich wieder eine neue Gattung erricliten wiirde.'^ 

 I quite agree with de Miij-rc that the species described by 

 him ought to be referred to the genus Ph irniosoma, for the 

 present at least. It, on the oilier hand, tiiere should prove to 

 be other species more nearly related to it than to the other 

 group of species, it would probably be justifiable to create a 

 new genus for them. Tlie genus Phonnosoma, indeed, seems 

 to me so different from the other Echinothnrids that 1 should 

 not be surprised if it eventually proved to form a separate 

 subfannly of the Echinothurids. 



De Meijere (' JSiboga' Ech. p. 250) finds it a drawback to 

 the new classification given by me in the ' Ingolt' Echinoidea 

 that new species do not always suit the diagnoses of the 

 genera given there, as, e. g., Phormosoma alternans. May not 



