176 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



DESCRIPTION OF TYPE SPECIES 



CASSIDULUS CARIBOEARUM Lamarck 



Plate 26, figures 3-7; text figures 148-150 



Cassiduliis carihoearum Lamarck, 1801. Systeme animaux sans vertebres, p. 349. 

 For complete synonymy see Mortensen (1948, p. 205). 



Material. — Two specimens studied from the Museum of Compara- 

 tive Zoology at Harvard, and three from the U. S. National Museum. 



Shape. — Small, largest specimen 31 mm. long, elongate, anterior 

 margin smoothly rounded, or slightly blunted posterior slightly trun- 

 cated by anal groove, sides expanding slightly posteriorly with great- 

 est width posterior to center. Adapical surface inflated with greatest 

 height anterior at apical system ; adoral surface flat. 



Apical system. — Anterior, monobasal, with four genital pores ; 

 according to Mortensen (1948, p. 207) genital pores first appear in 

 specimens approximately 13 mm. long. 



Ambulacra. — Petals approximately equal length, broad, slightly 

 closing distally. Interporiferous zones more than twice width of 

 poriferous zones, tapering slightly distally ; poriferous zones narrow, 

 outer pore larger than inner, slightly elongated transversely; inner 

 pore round, pores slightly conjugate (see pi. 26, fig. 6). Poriferous 

 zones unequal in length ; in petals V and I from three to seven more 

 pore pairs in outer series than inner; usually equal in petals II 

 and III, but in petal IV usually three more pore pairs in posterior 

 series than in anterior. Pores in ambulacral plates beyond petals very 

 small, single pore in each plate ; on exterior of test often in line with 

 outer pore of poriferous series (text fig. 148a), but on interior of 

 test always in line with inner series of pores (text fig. 148b). 



Periproct. — Supramarginal, transverse, two-thirds to four-fifths 

 distance from apical system to posterior margin, opening rounded 

 dorsally, pointed ventrally, overhung slightly by adapical surface; 

 flat groove equal in width to opening, extending to posterior margin. 



Peristome. — Large, pentagonal, transverse, anterior. 



Floscelle. — Bourrelets well developed, inflated, vertically sided. 

 Phyllodes (text fig. 149) single pored, widened, pores in single series 

 except in few instances where one pore displaced out of series, almost 

 occluded ; approximately four to six pores in each series, pores large ; 

 viewed from inside of test, pores in straighter line (text fig. 150) 

 with less widening of phyllodes. Buccal pores present. 



Tuherculation. — Tubercles with small perforate mamelons, large 

 vertical bosses. Adapically, tubercles small, with circular scrobicules ; 



