246 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



ward in reference to the pinnulars, and reaching downward to, or even between, 

 the sacculi. 



In its proximal third or half each tentacle contains a rather broad band of 

 matted small spicules along the distal side. 



Decametra mylitta. Near their distal border the ambulacral lappets contain 

 one or two long spicules, which may be straight or, in the distal portion of the 

 pinnule, may follow the outer distal curve. 



The tentacles contain a broad band of thickly matted spicules, which reaches to 

 the end of the proximal half. 



Decametra parva. Each ambulacral lappet contains an extremely delicate and 

 fine rod, very difficult to detect, directed outward and slightly distalward in refer- 

 ence to the pinnulars. 



The perisome between the line of sacculi and the pinnulars is without deposits. 



The tentacles occasionally contain very minute spicules near their bases. 



Decametra tigrina. Each ambulacral lappet usually contains a single fine, 

 nearly straight, spicule, directed outward and slightly distalward in reference 

 to the pinnulars, which may be very short. Sometimes there is a long, slightly 

 curved spicule along both the proximal and distal borders. 



At the base of the tentacles on the outer side there are a few minute spicules. 



Colobometra vepretum. Each ambulacral lappet contains a small straight or 

 slightly crooked rod directed outward and slightly distally in reference to the 

 pinnulars. 



Along the outer side the tentacles contain a median band of spicules, which 

 reaches to about the end of the proximal half. 



Colobometra discolor. Each ambulacral lappet contains a narrow straight 

 rod, extending outward and slightly distally in reference to the pinnulars, which 

 reaches downward nearly to the line of sacculi. 



Along the outer side each tentacle contains a continuous, rather broad, band 

 of spicules which reaches nearly to its tip. 



Prometra chadwicki. Each ambulacral lappet contains an extremely delicate 

 straight or slightly curved rod, which reached downward nearly to the sacculi. 



The perisome between the line of sacculi and the pinnulars is unplated. 



The tentacles contain few or no spicules. 



Cotylometra gracilicirra. Each of the ambulacral lappets contains a fine 

 straight rod reaching to the sacculi, which, in reference to the pinnulars, is directed 

 outward and slightly distalward. 



The perisome between the sacculi and the pinnulars is unplated. 



A continuous and very conspicuous band of small spicules runs along the 

 outer side of the tentacles almost to their tips. 



Oligometrides adeoncB (fig. 793, p. 372). Each ambulacral lappet contains a 

 very slender needle-like spicule, lying at right angles to the border of the pinnulars. 



The genital glands are completely covered by filmy plates, which are very 

 large along the line of sacculi, becoming small along the borders of the pinnulars. 



