THE STJB FAMILY ASTEANGIACE^. 399 



the upper parts of tlie primary and secondary costse much exceed 

 the others ; (2) the occurrence in some individual corallites of some 

 teeth on the margins of the largest septa (Verrill gives " sub- 

 entire primary and secondary " septa as a generic character for 

 Phyllangia, Tr. Conn. Acad. i. p. 532 ; and in Astrseidse proper 

 the dentation or not of the septal margins is employed by 

 Milne-Edwards and Haime to separate the Eusmilinse from the 

 Astrseinse). 



The few points above noted being too slight or too rariable to 

 distinguish the Malacca specimens from those found on the west 

 coast of America, the known distribution of P. dispersa assumes 

 the following remarkable condition : — 



Hob. Panama and Pearl Islands, "W. coast of America {Verrill) ; 

 Punta Arenas, Central America {coll. Mus. Brit.) ; Malacca {coll. 

 Mus. Brit, ex coll. Belcher). 



The Malacca specimen was (perhaps partly on distributional 

 grounds) originally identified as P. papuensis in the National 

 collection. 



I lay these observations before the Society feeKng that it is 

 only by careful observation and record of the constancy or incon- 

 stancy of the different characters in different groups that right 

 principles can be obtained for the distinction of genera and 

 species. 



DESOEIPTION OP PLATE XVI. 



Fig. 1. Phyllangia dispersa. Specimen from Malacca, upon valve of Cardita, 

 which also supports an incrusting Polyzoon. X 2 diam. 



2. The same. Part of the outer surface of a calicle from this specimen 



showing well-marked costse. X 6 diam. 



3. The same. Part of the outer surface of a calicle from same specimen, 



showing costse merely indicated. X 6 diam. 



4. The same. A calicle from same specimen, as seen from above. X 3 diam. 



5. Fhyllangia papuensis. Basal view of two calicles, from fragment of 



colony scaled off anchor from Amboyna, showing the characters and 

 distribution of the dissepiments. X 3 diam. 



6. The same. Part of a colony modified by growth around a seaweed or 



hydroid stem. X 2 diam. 



7. 8, 9. The same. Three calicles from large colony from Amboyna (fig. 10), 



as seen from above, to show range of variation in the columellar mass. 

 X 3 diam. 

 10. The same. Fine colony, showing great range in height of calicles and 

 characters of the columellar mass. X 2 diam. 



