27 6 
PACIFIC SCIENCE, Vol. XVII, July 1963 
Fig. 22. Cry stall op hris son inflatum. Sta. 2791. 
DISTRIBUTION: This species is known 
through six specimens, all from the San Pedro 
area including Redondo canyon, southern Cali- 
fornia, in depths of 177-420 fm. Three were 
found in mud, one in mud and gravel, and 
one in coarse sand. 
Crystallophrisson inflatum n. sp. 
Figs. 21, 22 
COLLECTIONS: 
2110 (3) in 427 fm. 
2791 (2) in 415 fm. 
DIAGNOSIS: This is a large species, with total 
length ranging between 25 and 35 mm, and 
greatest width 4 mm; the prothorax region is 
greatly inflated (Fig. 22). The hind end is 
provided with two lateral prolongations of the 
body wall which can be withdrawn into the 
circlet of thorns protecting the opening of the 
cloacal chamber and the adjacent glandular 
zone. Spines ( Fig. 21) are only very slightly 
or not at all keeled. The color in alcohol is 
dark gray with a brown tinge. The prothorax 
is whitish-brown, and the buccal plate is darker 
and shows three incisions on its dorsal edge 
of which the median one contains the mouth 
opening. The muscles are fairly thick, consisting 
of two pairs each of dorsal and lateral retrac- 
tors at the front end. In the anterior half of 
the prothorax there is a characteristic isolated 
small bundle of longitudinal muscles on both 
sides of the mid-dorsal line. Gill-retractor mus- 
cles are typical. The nervous system is also 
typical, with a brain situated very near the 
Fig. 23- Crystallophrisson marinellii. Characteristic 
spicules from body regions a, b, c, and d. 
