114 THE VOYAGE OF H.M.S. CHALLENGER. 



Amphiroa carina, n. sp. (PL XXXVL). 



Habitat. — Tropical and Subtropical Atlantic, Station 348 ; April 9, 1876 ; lat. 3° 10' 

 N., lone. 14° 51' W. Surface. 



Canary Islands, Lanzerote, February 1867 (Haeckel). 



Bract (figs. 14, l l J, and 21, ventral view; fig. 15, dorsal view ; fig. 16, apical view; 

 figs. 17 and 20, basal view; figs. 13 and 18, lateral view from the left side; fig. 12, 

 lateral view from the right side. Figs. 12 and 13 taken from immature Eudoxomes, 

 sessile on the stem). —The bract or hydrophy Ilium has a diameter of 6 to 8 mm., 

 and in general the form of a prompter's box ; it may be described as a bilateral poly- 

 hedron, which is composed of two four-sided prisms united perpendicularly ; the superior 

 or horizontal prism includes the two diverging horizontal phyllocyst canals ; the posterior 

 or vertical prism includes the large vertically depending phyllocyst. The obliquely 

 bevelled ventral face of the bract (the inferior face of the first, and the anterior face of 

 the second prism) is deeply excavated, and encloses the siphon and the gonophores. 



The horizontal apical or superior face (fig. 16) is trapezoidal, the ventral edge three 

 times as long as the parallel dorsal edge ; the two equal lateral edges are concave, as 

 long as the former, and diverge ventrally. 



The vertical dorsal or posterior face (fig. 15, ud), through which the phyllocyst (be) 

 shines, is also trapezoidal, the basal edge twice as long as the parallel apical edge and half 

 as long as the two lateral edges, which are slightly concave, and diverge towards the 

 base. 



The two lateral faces of the bract (figs. 12, 18, between ventral and dorsal faces) are 

 concave, irregularly pentagonal, nearly vertical, and divergent from the dorsal to the 

 ventral side. The superior horizontal and the posterior vertical edge of the pentagon 

 are the longest, of nearly equal size, and meet at right angles (in the apical corner of the 

 dorsal face). The vertical anterior and the horizontal inferior edge are only half as long- 

 as the former. The ventral (or antero-basal) edge of the pentagon, between the anterior 

 and inferior edges, is deeply emarginate and serrate. 



The horizontal basal or inferior face of the bract (fig. 17, ub) is nearly square, and the 

 smallest of all its six faces. Its ventral edge is bisected by the prominent median groove 

 of the bract-cavity. 



The ventral or anterior face of the bract (figs. 14, 21) has the most complicated form 

 of all six faces, and is deeply excavated by the cavity which includes the siphon and the 

 gonophores. The ventral opening of this cavity has again a trapezoidal outline ; its upper 

 horizontal edge is three times as long as the parallel basal edge, and somewhat longer 

 than the two dentate lateral edges which diverge upwards. The superior part of the 

 ventral face, above the opening of the cavity, is formed by a broad frontal face through 



