lOTBBOEDl \ "i m>ktii I'M nic \m> \hJ\. i K 163 



bulacrala; proximal end of furrow petaloid in form; ambulacra! • 

 much compressed bo that the tube feel stand in -i\ rows at the widest part of 

 furrow; interbrachial septum strongly calcified, and extending hIm.ui two-tl 

 toward center of disk; aperture from arm <•< >«-l< >rn into disk nnall about I 

 diameter of madreporite in ochraceus . a series of trail superactinal 



partitions or buttresses connects the adambulacral and inferomarginal plates, the 

 Bpaoes between them forming oelomic cavities abovt 



Papulae numerous, slender, in clusters, the actinal very long; the i 

 from a common hernialike swelling of the skin which, with bases of papula* 

 Mimed with tiny lanceolate pedicellariae. (PI 77. imach everaible; 



pyloric coecs long, bulky; intestinal coecum with Blender irregular lol \ .'id-. 

 extensive racemose tufts, opening dorsally, 



Small furcate straight pedicellariae (usually mingled with the 

 l-i • uliar to the genus and consist of a basal piece, longer than broad, and two curved 

 jaws each ending in two thin hyaline blades, characteristic for each Bpeciee One 

 blade is always much longer and broader than the other. L roid, 



le-hammer" pedicellariae with narrow to broad ovate jawB and terminal u 

 locking teeth are found scattered over the body but especially in the intermarginal 

 and in the actina] interradial channels; very amal] lanceolate dermal straight pedicel- 

 Inri: mmon especially among the papulae and in long pedunculate chu 



attached to the furrow margin, often surrounding one or more large lai 

 toothed pedicellariae Crossed pedicellariae, in dermal tufts or Burrounding spi 



numerous and lack any conspicuously enlarged terminal teeth ! uial 



fig I 



/.'. marks.- -The most characteristic features of this genus are the furcate pedicel- 

 lariae, which lire unique; the broad actinal urea; and the long adoral carina I 

 upward to the deeplj sunken, small, octinostome. These are all indications of ; 

 specialization, as are the very numerous, crowded, ambulacra] o nd small 



mouth plates. If we asaume as primitive a type similar to // *ith 



open oral angle (thai i-. without adoral carina . with biserial tul and 



uncrowded ambulacra] ossicles, no actinal plates, and few, regular, dorsolatei 

 then /' ■ ter is one of the most specialized genera in the family. It is n 

 ! in habitat, as specialized genera are likely to 1"'. b< 

 ific coasl of North America. 



Verrill (1914, p 87) la] lerable emphasis upon the 



pedicellariae as peculiar features of tin- genus, but this type i- widely distrih 



through ill"' family and i> in 00 way chai.i 



pedicellariae were diagnostic of i they would exhibit peculiarities for each 



- do the unique furcate pedicellariae Nothing similar to the latl 

 been described for any sea star No mention of them is made l>y Verrill, though 

 they are very numerous in hi papulosru i />■, '• a^ in other 



fori: thorn California races of P. ■■ and /' 



are rathi i 



The Bpeciee are extremely \ ariab 

 rial i- availal fie distinctions become lees distinct. Three -i rply 



differentiated, without the least indication of intergradation All the other 



