21 



h. Armor arched dorsally, flat or slightly convex ventrally ; spines 

 or teeth usually present at anterior dorsal margin of the armor. 

 (fi<'. 30). Brachionid.K, Brachionus. 



hh. Armor of different structure, 

 i. Armor an irregular oblong or ellipsoidal box, marked with 

 grooves and sometimes with vesicles closed behind, open ven- 

 trally for the protrusion of the foot ; foot ending in two toes 

 and situated on ventral side of the body. (Fig. 37). 



Plcesomatid^, Plcesoma. 

 ii. Armor compressed laterally ; covering entire body excepting for 

 two round openings ; without distinct grooves and sculpture 

 (fio-. 38). Gastropodid-K Gastropus. 



ff. Foot not transversely wrinkled nor ringed, though often jointed. 

 g. Armor unsymmetrical, of one piece, cylindrical, fusiform, ovate or 

 conical, closed all around but open at each end, smooth, rather 

 thin ; one eye ; foot very short, with one or more very slender, 

 stiff, bristle-like toes. Rattulid^. 



h. The two toes equal or the shorter more than one-third the length 

 of the longer (fig. 20). DiurcUa. 



hh. A single toe usually with an inconspicuous shorter one not more 

 than a third the length of the longer (fig. 21 ). Rafiulus. 



gg. When viewed dorsally the armor is symmetrical, 

 h. Armor cleft down the middle of the back by a fissure whose sides 

 are united by membrane ; open at both ends for the projection 

 of the head and foot ; toes blade shaped. 

 i. Armor only slightly developed, covering only the dorsal half of 

 the bodv ; median fissure not strongly marked ; one eye. 



DiASCHiziD.^, Diaschiza. 



ii. Armor well developed, an oblong box enclosing the body, open 



at both ends and distinctly cleft down the back. Salpinid.-e;. 



j \rmor with neither anterior nor posterior spines ; eye usually 



wanting. Diplax. 



jj. Armor with spines either anteriorly or posteriorly or both ; 



eye present (fig. 23, 24^. My it Una {Salpiiia). 



hh. Armor not dorsally cleft. 



i. Armor only laterally cleft, of two plates, the ventral one nearly 



flat ; foot proper short and inconspicuous, of one or two joints ; 



body ending in one or two large rod shaped toes, one eye. 



Cathypriad.B. 



j. Toes two. 



k. Armor subcircular or broadly ovoid with wide and deep 



lateral furrow ; mainly larger species. Cathypria. 



kk. Armor longer, usually a long ellipse, open in front ; lateral 



furrow not pronounced. Distyla. 



jj. One rod shaped toe (fig. 26). Monostyla- 



ii. Armor of a different structure or foot with three segments. 



j. Armor of a single piece, like a coat covering only the anterior 



half of the dorsal surface of the body or less ; foot long, 



jointed, with two minute toes, {Cochleare) or head sur- 



