10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Distribution. — The species has been reported from the type- 

 locality (Theel, 1886b, p. 15), Porto Seguro, Brazil. Deichmann 

 (1930, p. 193) recorded numerous specimens from Buccoo Bay, 

 Tobago, British West Indies. In a later publication Deichmann 

 (1954, p. 401) noted that this species occurs in "shallow water, 

 attached to rocks or seaweeds." 



Lissothuria antillensis, new species 



Figure 3 



Diagnosis. — Dorsal scale covering complete. Deposits of dorsal 

 surface are perforated plates, towers, and cups; no hourglass-shaped 

 deposits. Deposits of sole are knobbed plates and cups. Tentacles 

 with rosettes. 



Description. — Body elongate, about twice as long as broad, mouth 

 anterodorsal, anus dorsal. Dorsal surface of body arched, sole flat, 

 rectangular. Dorsal surface with thick imbricating scales approx- 

 imately 1.5 mm in diameter; 7 scales between mouth and anus. 

 Scales perforated for passage of tube feet, which are scattered over 

 dorsal surface; sometimes 4-5 feet pass through one scale. Oral 

 valves of varying shape, sharply pointed distally, interradial valves 

 larger than radial valves. Scales overlaid by thick soft integument 

 filled with calcareous deposits. 



Sole with 2-3 rows of larger tube feet along left and right ventral 

 radii (in addition to single row of smaller marginal feet) . Midventral 

 radius with tube feet throughout, 3 rows anteriorly and posteriorly, 

 1-2 rows near center of sole. 



Color in alcohol light to dark brown; tentacles dark brown. In- 

 ternal anatomy not examined. 



Calcareous deposits of dorsal surface (apart from scales) are per- 

 forated plates, towers, and cups. Perforated plates small, smooth, 

 average greatest length 0.1 mm (fig. 3e); larger plates occasionally 

 found. Towers complex, with dentate apex; average height 0.18 mm, 

 average diameter of base 0.15 mm (fig. 3g), Deep cups (fig. 3a) 

 common on dorsal surface; cups typically with 4 large perforations 

 and 4 conspicuous knobs projecting from underside. Cup rim of 

 variable shape, with numerous irregular projections. No hourglass- 

 shaped deposits found. 



Sole deposits are plates and cups. Plates 0.1 to 0.12 mm in length, 

 oval to rectangular, perforated, with low rounded knobs around margin 

 and in center (fig. 3b). Cups of average diameter 0.074 mm, shallow, 

 resembling buttons, with 4 larger perforations and some scattered 

 smaller perforations; margin and center of each cup with low rounded 

 projections (fig. 3f). 



