Table 4. — Spinocalanus and Mimocalanus, Al armature. 



2e 



le 



le 



Males, genera 

 equivalent 



Males, genera 

 differ 



Males, species 

 differ 



's = seta; e = esthete; side (1) may be right (rt) or left (It), side (2) is the remaining side. 



above, occurred only in female segment 1, which is 

 easily damaged during dissection. 



There are slight specific differences in Al between 

 some Spinocalanus males, especially in relation to the 

 merging of segment 20 to 21, which occurs on either 

 the left or the right side, depending on the species (see 

 Figs. 29 and 59). The merged, and apparently "lost," 

 segment 20 may or may not be represented by 1 seta, 

 but never by an esthete. If there is no seta on the 

 "lost" segment 20, the complete and distinct segment 

 20 on the opposite Al bears either 1 seta or 1 esthete. 

 If there is 1 seta on the "lost" segment 20, the com- 

 plete segment 20 on the opposite Al bears 1 esthete. 

 Other specific differences are noted in the descrip- 

 tions. In Table 4 and the discussion of deviations, 

 Roman numerals are Al segments; Arabic numerals 

 are numbers of setae (s) and numbers of esthetes (e). 

 The armature of segment 2 in females is distributed as 

 follows (see Fig. 13): proximal, 2 setae; midlength, 2 

 setae, 1 esthete; distal, 2 setae. The armature of seg- 

 ment 2 in males is distributed as follows (see Fig. 29): 

 proximal, 2 setae, 1 esthete; midlength, 2 setae, 2 es- 

 thetes; distal, 2 setae, 1 esthete. In addition to 

 anterior armature, segments 22-24 have 1 posterior 

 seta; segment 25 has 1 posterior and 2 terminal setae. 

 P^sthetes are only on the anterior edge, somewhat ven- 

 tral to setae. 



Not enough material of Monacilla and Teneriforma 

 was available to warrant generalizations for Al ar- 

 mature; published information is also insufficient. 



A2 usually is unbroken, although some setae may 

 detach. In dissecting it is difficult not to detach these 

 setae, both while cutting the appendage and while un- 

 tangling it from the remaining appendages. 



Mn palp has very long setae, especially on Re, and 

 these are easily broken while removing the append- 

 age. The blade is "capped" by thin, extremely fragile 

 teeth. The main body of the blade, which is much 

 stronger, has a foundation of "teeth," but the actual 

 biting surfaces are the fragile "caps." The 90° twist of 

 the Mn blade requires that the blade itself be cut 

 across at about half its length, so that it will lie flat 

 when mounted, but successful cutting is difficult 

 because of the fragile teeth. 



Mxl setae are long and fragile. The female 

 gnathobase is strong and seldom damaged. 



Mx2 has some very small setae which are difficult 

 to see in all preparations, although most setae are 

 strong and not too fragile. The outer seta, if present, is 

 undoubtedly very fragile and was intact on only a few 

 specimens. 



Mxp usually is present and provides important 

 characters. Some of the armature is fragile, however, 

 especially Bl-2 transverse spine-combs, if present, 

 and the Ri4-5 outer setae in most species. 



The fragility of the swimming legs has held back the 

 study of the Spinocalanidae. Specimens usually have 

 complete PI, but only infrequently P2, and specimens 

 with P3 or P4 are rarities. Ri are less often detached 

 than Re, so that if there are a few specimens of a 



