310 PEor. p. M. DuisrcAN on the 



Pacliyseris. There are no separate calices to be seen ; and it 

 appears to consist of long concentric ridges separated by low 

 valleys, tbe elevations being produced by vast numbers of septa 

 placed side by side. Its species resemble corals less tban tbose 

 of Mceandrina, and yet they may be said to be mimetic types. 



Pacliyseris is the fullest development of the serial calicular 

 arrangement ; there are no individuals in a series, and it is all 

 one long calice with its septa passing in one direction, over the 

 coUine, to those of the next calice in order from within outwards, 

 and in the other sinking down along a line wbere there is a colu- 

 mellary space and percbance a columella. 



The following is its diagnosis according to MM. Milne-Edwards 

 and Jules Haime (' Hist. Nat. des Corall.' vol, iii. p. 85) : — The 

 corallum is compound, adherent, foliaceous, and very variable in 

 shape. The coUines are arranged in simple series, those of each 

 series being completely confounded with ea,ch other. The series 

 are separated by unequal-sized "collines. The septa are delicate 

 and close. The columella is tubercular, moniliform, and generally 

 tolerably distinct. The basal wall is naked and finely striated. 



In explanation, the authors notice that the genus contains 

 those rungidse the calices of which completely unite in series, 

 losing all individuality as in McBandrina. 



MM. d'Archiac and Haime described a species from the Num- 

 mulitic of Sind ; and it is stated to have been found also at 

 St. Bonnet in the French Eocene. 



This form I found was a characteristic species of the Lower 

 Eocene of Sind beneath the great development of Nummulitic 

 limestone *. 



Two well-developed species with the details on a grand scale 

 were described from the Miocene (Gdj) of Sind. In one, Pa- 

 chyseris exarata, nobis, the septa are unequal, and there is a colu- 

 mella ; whilst in the other, P. affinis, the columella is rudi- 

 mentary "f. 



Four recent species are known, and in P. rugosa, Lamk., sp., 

 the septa are alternately slightly unequal and slightly enlarged 

 near the columella ; in P. speciosa, Dana, sp., there is more irre- 

 gularity of septa and a well-developed columella ; in P. Icsvicollis, 

 Dana, sp., the inequality is evident and the columella is rudimen- 

 tary ; and, finally, in P, Valenciennesi, Edw. & Haime, the septa 



* ' Fossil Corals and Alcyonaria of Sind,' Pal. Ind. ser. xiv. 1880, pi. xiv. 

 t Ibid. p. 96. 



