GEODIA ATAXASTRA. 



89 



like those predominant in var. angustana, are rare in var. latana, one, two, or 

 even all three clades (Plates 44, fig. 13) being reduced in length and terminally 

 rounded in most of the mesoproclades observed in this variety. Most of the 

 pointed, fully developed clades are angularly bent outward in the middle like 

 some of the clades of the mesoproclades of var. angustana (Plate 44, fig. 14). 

 The dimensions of the cladomes of the mesoproclades of var. latana are : length 

 of longest clade of the cladome 25-58 fi, mostly 32-50 //; length of epirhabd 28- 

 50 pL, mostly 34-47 [x; angle between clade-chord and epirhabd axis 25-58°, on 

 an average 43.6°. 



The large anatriaenes (Plate 44, figs. 15-23, 40d, 41) have in var. angustana 

 a rhabdome 2.1-3.1 mm. long and, at the cladome, 3-10 fi thick. In var. latana 

 the anatriaene-rhabdome is somewhat shorter and thicker, measuring 2.-2.8 

 mm. in length and 7-12 // in thickness. The cladomes are generally regular, 

 irregular anatriaene-cladomes with one clade shorter than the others (Plate 44, 

 figs. 17, 41) being rare. Exceptionally all three clades are greatly reduced 

 in length, so that the whole cladome appears as a three-lobed tyle (Plate 44, fig. 

 23). In the anatriaenes of var. angustana the cladome is usually destitute of an 

 apical protuberance. The clades of these anatriaenes are regularly conical, 

 taper uniformly to a sharp point, are strongly curved, concave to the rhabdome 

 basally, straight or just perceptibly bent outward distally, and 17-68 /i, mostly 

 30-65 fi long. Their chords enclose angles of 20-42°, on an average 34°, with the 

 axis of the rhabdome. The cladomes of the large anatriaenes of var. latana 

 are different in appearance. Most of them have a distinct apical protuberance 

 and their clades are very thick and not very strongly curved, concave to the 

 rhabdome at the base, and abruptly attenuated to very slender, straight or 

 slightly outwardly curved, sharp-pointed tips. They are 30-55 fi long, their 

 chords enclose angles of 41-55°, on an average 47°, with the axis of the 

 rhabdome. 



The minute dermal anaclades (Plate 44, figs. 28d, 42, 46-49), which have 

 been observed only in var. angustana, have a slightly curved rhabdome 190-340 /< 

 long. At the cladomal end it is 0.5-2 /j. thick, and it increases in thickness 

 towards the middle to 1.4-3.5 /i, the central part of the rhabdome being usually 

 not quite twice as thick as its cladomal end. The acladomal end of the rhabd- 

 ome is rounded and usually slightly thicker, rarely thinner, than the cladomal 

 end. Most of these minute anaclades are regularly triaene. The basal parts 

 of their clades are generally quite strongly curved, concave to the rhabdome, 

 while their central and distal parts are straight. The chords of the clades are 



