The Genus Riccardia in Chile. 143 



9. Riccardia corralensis (Steph.) comb. nov. 

 Aneura corralensis Bull. Herb. Boissier 7: 742. 1899. 



Specimens examined: on earth, Port Corral, 1896, Duscn 516 

 (St., type of Anciira corralensis). Known only from the type 

 locality. 



The branching of R. corralensis is fairly regular and the distinc- 

 tion between the main axis and those of lower rank is clear. At 

 the same time the differentiation of the thallus, both in its gross 

 structure and in its histological features, is less marked than in the 

 species which have gone before. The plants grow in compact tufts 

 and are pale green, becoming brownish with age. So far as the 

 material at hand indicates they are at first prostrate but gradually 

 turn upward, so that the apical portion assumes an ascending or 

 suberect position. In spite of their apparent delicacy the plants 

 exhibit a considerable amount of rigidity. Neither rhizoids nor 

 clearly differentiated stolons have as yet been demonstrated. 



The main axis shows long-continued growth. In some cases the 

 apex was blunt, showing that growth had not yet been suspended ; 

 in other cases the axis gradually uarrowed to a blunt point, showing 

 that growth had come to an end (Fig. 4, A). The axis is usually 

 only 1.5-2 cm. long, 0.35-0.5 mm. wide, and 0.25 mm. thick. It 

 is distinctly flattened but shows a biconvex outline in cross section 

 (Fig. 4, B), the ventral convexity being greater than the dorsal. 

 At the ends the section varies from rounded to subacute, and the 

 margin sometimes shows in surface-view an interrupted and 

 irregular row of cells or even a double row, never distinct enough 

 to be called a wing. The median portion of the axis is mostly eight 

 to ten cells thick. The cells of the superficial layer are slightly con- 

 vex and distinctly smaller than the interior cells. In the median 

 portion of the axis they average about 17 /a in width; toward the 

 margin they gradually increase to a width of 20-25 /x. The 

 interior cells average about 140x40;^. The cells are thin-walled 

 throughout. 



The primary branches spread obliquely and are given oft' from 

 the main axis at intervals of 1-3 mm. In rare instances a primary 

 branch represents a new axis, but it is usually limited in growth 

 after attaining a length of 2-4 mm. The ordinary primary 

 branches are mostly 0.15-0.3 mm. wide and may be either blunt or 

 pointed at their apices. On each side they usually give off two or 



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