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much along its course. The radula is powerful 
but without real teeth or denticles. All three 
kinds of salivary glands are present. Buccal 
glands occur only in front of the sphincter 
muscle. The mid-gut is very wide. The peri- 
cardium is notably large, the ventricle highly 
muscular and there are two atrioventricular 
openings. The dorsal vessel originates as a con- 
spicuous ampulla situated in the pericardium. 
Reproductive organs are without peculiarity. 
The ciliated portion of the gonoduct is rather 
long; the gonoduct openings are on papillae, 
their epithelium not continued on the wall of 
the cloacal chamber. 
distribution: Four specimens, all from the 
San Pedro area of southern California, were 
taken in depths of 16-429 fm, in mud or 
sandy mud. 
Fig. 25. Crystallophrisson rectum. Characteristic 
spicules from body regions c and d. 
FIG. 26. Crystallophrisson rectum. Sta. 2798. 
Crystallophrisson rectum n. sp. 
Figs. 25, 26 
COLLECTIONS: 
2644 (1) in 310 fm, with Limifossor fratula 
and C. hartmani. 
2798 (1) in 386 fm, with Prochaetoderma 
calif ornicum and C. hartmani. 
DIAGNOSIS: These animals are moderately 
large (Fig. 26) being 10-18 mm long, and 
having an average diameter of 1—1.5 mm. The 
prothorax may reach 2.5 mm in diameter. The 
color is yellowish-brown. The spines (Fig. 25) 
are weak and have little structure. The buccal 
plate is semicircular and has a deep and wide 
dorsal cleft which contains the mouth opening. 
The cuticle is very thin, the abdominal gland 
zone present. The subepidermal muscle layers 
are weak; there are three pairs of dorsal, three 
pairs of lateral, and several pairs of ventral 
