COMPENDIUM OF GENERIC DISTINCTIONS 



-80S 



Family. SYNAPTADJE. Suckers none. 

 Genus. SYNAPTA. Body cylindrical, slender, long. Ten- 

 tacles long, and fingered at tips. 



Order. ECHINOIDEA. Shell chalky, either spherical 

 or disc-like, formed of immoveabie plates. Locomotion by 

 spines and suckers. 



Family. CIDABIDJE. Body globular. Mouth above 

 and vent below, in centre of body. Five unbroken avenues. 

 Teeth complicated. 



Genus. ECHINDS. Spines of same form, the knobs of 

 shell not perforated. 



Genus. CIDARIS. Spines of several forms ; knobs of 

 shell perforated. 



Family. SPATANGID.53. Mouth below, not in centre. 

 Vent at one side. Avenues not continuous. Teeth wanting. 



Genus. SPATANGUS. Body heart-shaped, flattened. 

 Avenues above and below. No dorsal impression. 



Genus. AMPHIDOTUS. Body heart-shaped, convex. An 

 impression in four of the dorsal avenues. 



Genus. BRISSUS. Body heart-shaped, convex , dorsal 

 impression enclosing avenues. 



Family. CLYPEASTEEID^E. Mouth and vent both 

 below ; mouth in centre, toothed. Avenues not continuous. 



Genus. ECHINARACHNIUS. Body nearly circular, very 

 Hat, e Ige nearly entire. Avenues short. Vent between 

 mou'n and hinder edge. 



Genus. ENCOPE. Body flat, nearly circular, lobed and 

 pierced with keylike-shaped holes. South America. 



Genus. ROTULA. Body flat, front of disc cut into deep 

 teeth ; hinder edge not lobed, nearly entire. South 

 America. 



Sub-class. HYPOSTOMATA. Stomach sac- 

 like, only one aperture. Body lobed or rayed. 



Order. ASTEROIDEA Shell composed of many 

 moveable pieces. Skin sometimes leathery, sometimes cal- 

 careous. Digestive canal symmetrical. 



family. ASTEKIAD^!. Rays developed from body. 

 Locomotion by suckers under rays. 



Genus. ASTERIAS. Body star-shaped. Rays flattish and 

 short, edged with plates. Avenues edged with three sets of 

 spines, two rows of suckers in each avenue. 



Genus. UR ASTER. Body rather conical, rays rounded, 

 two rows of suckers in each avenue, and three sets of spines. 



Genus. GONIASTER. Body conical, edged with spiny 

 plates. Avenues edged with cross rows of spines. 



Genus. ASTERINJE. Body covered with short spines on 

 both surfaces. Avenues edged with a single row of spines. 



Genus. PALMIPES. Body flat, thin, with small tufts of 

 spines., Avenues edged by longitudinal tufts of spines. 



Genus. SOLASTER. Many rays, covered with tufts of 

 spines. Avenues edged with three sets of spines, and fur- 

 nished with two rows of suckers. 



Genus. CRIBELLA. Rays few, covered with spiny tuber- 

 cles. Avenues edged with two sets of spines. 



Family. OPHITJRIDJE. Rays long, affixed to round disc 

 like the body of an Echinois. Locomotion by suckers. 



Sab-family. Ophiurina. Rays simple. 



Genus. OPHIURUS. Rays scaly, prolonged at disc. 

 Large shield-like plates at origin. Threads between spines 

 simple. 



Genus. OPHIOCOMA. Rays scaly, not prolonged at 

 disc. Small pentagonal plates at origin. Threads between 

 spines pinnate. 



Sub-family. Euryalina. Rays rmich branched. 



Genus. ASTROPHYTON. Rays repeatedly two- branched. 



Order. CRINOIDEA. Digestive canal not sym- 

 metrical. Chalky shell formed of many moveable pieces. 



Genus. COMATULA. Rays five, pinnate. When adult, 

 free ; when young, seated on stern. 



Genus. PENTACRINUS. Permanently on long footstalk, 

 which is pentagonal and formed of numerous joints. Fila- 

 ments placed* in whorls on footstalk, which does not alter in 

 liameter. Warm seas. 



CLASS-ACALEPIIA. 



Radiate, gelatinous, free A digestive cavity with ra- 

 diating tessels Poison-threads Metamorphosis. 



Order. SIPHONOPHORA. Body irregular. No 

 central digestive cavity. With sucking organs. Locomotion 

 by contractile cavity or sacs filled with air. 



Family. VELELLAD.32. Animal stretched over gristly 

 plate. 



Genus. VELELLA. Body flat, oval. Oblique crest above ; 

 tubular mouth below, surrounded by short tentacles. 



Family. PHYSALIAD5!. Animal a large air-filled sac, 

 with many tentacles. 



Genus. PHYSALIA. Air-sac large, oblong, crest-wrtnkled. 

 Tentacles near one end, long, variously-shaped. 



Family. DIPHYID.33. Animals bell-shaped, double, 

 fitting into each other. 



Genus. DlPHTES. Animals pyramidal, a few points' 

 round aperture. 



Order. CTENOPHORA Body symmetrical, not disc- 

 shaped. Large central digestive cavity. Locomotion by 

 parallel rows of cilia. 



Family. CALLIANIRIDJE. Two long, contractile fila- 

 ments in chambers, one on each side. 



Genus. CYDIPPE. Body globular, no lobes nor tentacles. 



Family. BEROID./E. No contractile filaments nor 

 chambers. 



Genus. CESTUM. Body very flat, wide, and short, edged 

 with cilia. Hot seas. 



Order. DISCOPHORA. Body disc-shaped, oval, or 

 less convex. Large central digestive cavity. Locomotion 

 by expanding and contracting disc. 



Trtbe. GYMNOPTHALMA TA. Eye-specks uncovered 

 'or wanting. Circulating vessels running to margin, either 

 simple or branched. 



Family. SARSIADJE. Vessels simple, four. Ovaries in 

 substance of footstalk. 



Genus. SARSIA. Hemispherical ; four tentacles at edge 

 of vessels. Eye-specks four. Stomach in extensile footstalk. 



Family. WILLSIAD5!. Vessels branched. 



Genus. WILLSIA. Globular. Ovaries six. Vessels six. 

 Eye and tentacle opposite each branch. Footstalk short. 



Family. ^IQUOREAD^E. Vessels more than eight. 

 Disc flattish. Ovaries in a line along vessels. 



Genus. ^EQUOREA. Disc rather convex. Vessels very 

 numerous. Footstalk wide, cleft into many broad lobes. 

 Tentacles slender. 



Genus. EUDORA. Disc very flat. No tentacles nor foot- 

 stalk. Hot seas. 



Tribe. STEGA NOP THA LMA TA .Eye-specks covered 

 by flaps. Circulating vessels forming a network. 



Family. MEDUSAD/E. Stomach with a mouth, through 

 which solid food is taken. 



Genus. CHRYSAORA. Disc hemispherical, lobed. Many 

 tentacles on edge. Four very long furbelowed arms, not 

 fringed. 



Genus. MEDUSA. Disc hemispherical. Many tentacles 

 on edge. Eyes eight. Ovaries, chambers, and fringed arms 

 four ; one opening in centre, four at sides. 



Genus. CYANEA. Disc flattened, rather scolloped ; four 

 fringed arms. Tentacles of edge very numerous, set 

 beneath disc. 



Family. RHIZOSTOMAD.32. No central orifice to 

 stomach. Food received through ends of branching canals. 



Genus. RHIZOSTOMA. Ovaries four. Footstalk with four 

 or eight semilunar apertures. 



CLASS. ZOOPHYTA. 



Radiate, gelatinous, or fleshy, with tentacles round mouth 

 Stinging tcectpons. 



Order. ACTINOIDA. Internal cavity enclosing 

 stomach, and divided into compartments by radiated walla. 

 Germs thrown out of cavity at sea. 



