THE APODOUS HOLOTHURIANS 159 



DD. Fusiform bodies with flat, widened ends, or replaced by more or less elon r 



gated perforated plates. 



E. Fusiform bodies largely replaced by big perforated plates (plate x, 

 fig- 18). 



Some of the tables with discs having 40-60 holes (plate x, fig. 



17) MAROCCANA 



No such tables. LORICATA 



EE. Fusiform bodies transformed into very flat rods or narrow plates, 

 with an expanded middle portion. 



Ends of the flat rods expanded and perforated (plate x, fig. 19). 



PERFORATA 



Ends of the narrow plates not expanded and perforated. 



PAUPERA 

 BB. No colored phosphatic deposits present in the skin. 



C. Skin thin, often translucent, and usually more or less rough; tail usually abrupt 



and slender. 



D. No supporting rods or elongated fusiform bodies present in caudal region. 



E. Tables very small, regular, with disc about 100 /, in diameter, usually 



with 3, but often with more, holes; spire 150 /* high, or even more. 



BLAKEI 



EE. Tables much larger and spires proportionally much lower. 



F. Skin very thin and delicate, gray, with more or less yellowish- 

 brown coloring anteriorly and dorsally; deposits in body-wall, 

 except in caudal region, usually wanting in specimens over 40 

 mm. long; in caudal region (and in body-wall of young speci- 

 mens), tables with more or less circular discs, perforated by 



6 or more large holes, are generally present ANTARCTICA 



FF. Skin not so thin and delicate; not so colored; tables abundant 

 in body-wall. 



Tables with rounded, regular discs, with 3-6 (rarely more) 



circular holes PARVA 



Tables with more or less irregular disc; holes usually oval, 



with outer end somewhat pointed ARCTICA 



DD. Conspicuous supporting rods present in caudal region. 



E. Large, smooth, irregular plates, with 60-70 holes present. .AGASSIZII 

 EE. No such plates. 



F. Spires of tables and of caudal supporting rods also, with a greatly 



expanded and spiny top ELONGATA 



FF. Spires not commonly with an expanded and spiny top. 



Supporting rods of caudal region with wide ends and a 

 prominent spire (plate x, fig. 20) ; tables with a tapering 

 spire, commonly of a single piece (plate x, fig. 21). 



ORANULATA 



Supporting rods with tapering ends and a low central pro- 

 jection. 



Tables with a spire of 3 or 4 rods united by 4 or 5 cross- 

 bars (plate x, fig. 22) DISPAR 



Tables not provided with such a spire MUSCULUS 



CO. Skin thick, smooth, and leathery ; posterior end of body tapering, but a distinct 

 caudal appendage is wanting ". . . ARENICOLA 



