1118 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
EXPLANATION OF DESCRIPTIVE TERMS. 
The technical terms in starfish descriptions are rather numerous. On account 
of the large number of new forms in the Hawaiian collections, it has been necessary 
to give rather thorough descriptions, more especially as certain of the species belong 
to new and often obscure genera. The following glossary is supplied for students 
unacquainted with starfishes: 
abactinal, pertaining to the dorsum or back, as opposed to actinal. 
abactinal area, usually used in speaking of the abactinal paxillar area of phanerozoniate species. 
actinal, ventral, used in speaking of the surface on which the mouth opens. 
actinal intermediate plates, plates paving the actinal surface, between the inferomarginal and adambula- 
cral plates. 
actinal interradial areas, actinal area of disk, paved with actinal intermediate plates. 
actinolateral membrane, membrane uniting the actinolateral spines. (PI. xl, fig. 1.) 
actinolateral spines, in the Pterasteridse the long spines articulated on the body-frame close to the adam- 
bulacral plates which form the lateral or marginal web in Pteraster, and support the whole actinal 
floor in Hymenaster. See plate xl, figure 1. 
actinostome, the opening in the actinal skeleton bounded by the mouth plates and first adambulacral 
plates. 
adambulacral plates, plates bordering ambulacral furrow. 
ambulacral furrow, the V-shaped furrow running the length of the rays, in which are the tube-feet; 
actinal in position. 
ambulacral plates, plates roofing the furrow. 
aperture papillse, in the Pterasteridse, papilliform spines opposite the segmental apertures. ( PL xxxvm 
fig. 6, ap. p. ) 
bivatved, see pedicellaria. 
excavate, see pedicellaria. 
fascioles or fasciolar grooves, grooves between special transverse ridges of the marginal plates, occurring 
over the suture between plates; usually bordered by specialized spinelets. (PI. iv, fig. 2, shows 
several fascioles cleared of spines. ) 
foraminate, see pedicellaria. 
forcipiform, forficiform, see pedicellaria. 
furrow, the ambulacral furrow. 
furrow spines, used sometimes in referring to the spinelets on the furrow margin of the adambulacral 
plates. 
inferomarginal plates, the lower or ventral series of marginal plates, usually very prominent in all the 
Phanerozonia. 
interbrachial arc or angle, arc between 2 adjacent rays. 
madreporic body, the more or less prominent calcareous sieve marking the external opening of the 
water- vascular system, situated in an interradius of the abactinal area. 
marginal plates, the more or less prominent plates defining the contour of the body in the Phanerozonia; 
usually discernible in other orders. 
mouth plates, the modified innermost adambulacral plates. 
osculum or oscular orifice, the large central opening guarded by valves in the supradorsal membrane of 
the Pterasteridse. 
papula ', the small vermiform, or occasionally compound, dermal branchiae which protrude through 
holes in the skeleton. 
papular, pertaining to pupulse. 
papularium, specialized papular area of Pontasterinse. 
