28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Apical system. — Slightly anterior, tetrabasal (text fig. 4) oculars 

 11 and IV in contact separating genital plates 2 and 3 from genital 

 plates I and 4 ; complementary plates present in some specimens. 



Ambulacra. — Petals slightly developed, long, extending to margin, 

 widely open with very broad interporiferous zones, four or five times 

 width of poriferous zones; petals V and I with slight curve; outer 

 pore of pair elongate transversely, inner pore round, conjugate. 



Adoral inter ambulacra. — Two series of low, alternating plates; in 

 interambulacrum 5 plates larger than in other areas. 



Periproct. — Supramarginal, opening in contact with apical system, 

 longitudinal with groove continuing from opening to posterior margin. 



Peristome. — Anterior, depressed, oval longitudinally. 



Floscelle. — No bourrelets; phyllodes (text fig. 5) double pored 

 with many pairs of pores arranged in three series in each half- 

 ambulacrum, five or six pairs of pores in each series ; phyllodes not 

 expanded ; no buccal pores. 



Occurrence. — Middle Jurassic (Bajocian to Bathonian) of France 

 and England. 



Location of type specimens. — According to Lambert and Jeannet 

 (1928, p. 126) the type specimens are at the Museum of Carlsruhe. 



Remarks. — Mortensen considered that the ambulacra were not 

 petaloid. However, the pores on the adapical side are not the same 

 size or shape as those on the adoral side. Adapically, they are large 

 and unequal, the outer being transversely elongate. Adorally they 

 are much smaller, equal, and in peripodia. Furthermore, the pore 

 pairs on the adoral side decrease in size near the margin. 



Synonym of HYBOCLYPUS 



Aiilacopygus Pomel, 1883, Class, meth., p. 53. Type species by monotypy, 

 Hyboclypus caudatus Wright. 



DESCRIPTION OF TYPE SPECIES 

 HYBOCLYPUS CAUDATUS Wright 



Plate I, figure 5 ; text figures 6, 7 



Hyboclypus caudatus Wright, 1851. Ann. Mag. Nat. Hist., sen 2, vol. 9, 

 p. 100, pi. 3, fig. 2. 



Material. — The holotype and 16 other specimens including a 

 figured specimen were studied in the British Museum (Natural 

 History) ; four specimens were seen in the Lambert Collection at 

 the Sorbonne, Paris, and one in the U. S. National Museum. 



Shape. — Small, average specimen 20 mm. long, elongate, anterior 

 margin gently rounded or slightly blunted, posterior slightly pro- 



