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



of it, I find that it differs from two other forms which I have myself observed living, 

 Alophota giltschiana, from the Canary Islands (PI. XXVI. figs. 1-3), and Alophota 

 mertensii, from the Indian Ocean. The description of the latter will be published in 

 my Morphology of the Siphonophorse. 



Alophota giltschiana, n. sp. (PI. XXVI. figs. 1-3). 



Habitat. — North Atlantic ; Canary Islands, Lanzerote, December 25, 1866 (Haeckel). 



Corm (fig. 3, lateral view of the mature corm, from the right side; fig. 1, a young, 

 monogastric, larva ; fig. 2, an older, polygastric, larva). — The largest corms observed 

 which possessed gonodendra at the base of the siphons had a diameter of 15 to 20 

 mm., and were of a greenish-blue colour. The common trunk and the basal ampullae of 

 the tentacles were light greenish, the pneumatosaccus, the siphons, and the tentacles 

 blue, the siphons with numerous black patches — the hepatic villi. The colour of the 

 ripe gonodendra (placed on the right side) was yellowish. The body of the young 

 larvae, without gonodendra (figs. 1, 2), was entirely blue- coloured, or with a few greenish 

 portions here and there. The smallest larva observed (fig. 1) was monogastric, 4 mm. 

 long and 1 mm. thick, and had a pneumatophore 1 mm. in length. This Cystonula was in 

 the contracted state very similar to that figured by Huxley of Physalia (9, pi. x. fig. 1). 

 Pneumato'phore. — The expanded float of the ripe corm (fig. 3) is ovate, with sub- 

 horizontal axis. The apical or anterior pole is pointed and bears the stigma or the 

 opening for the emission of gas (fig. 3, po). The opposite basal or posterior pole is 

 rounded and bears the protosiphon, or the primary polypite of the larva (su), and 

 attached to its base a single tentacle with a basal ampulla. This distal or primary 

 cormidium is separated by a broad interval (the basal internode) from the ventral 

 group of ordinate cormidia, which form a single series in the ventral median line of 

 the pneumatophore ; they occupy only the middle third of its ventral side, whilst 

 the anterior third and the posterior third (or the basal internode) are naked and 

 free, without appendages. 



Cormidia. — The number of secondary cormidia which compose the ventral group is 

 in the specimen figured (fig. 3) four, besides a young one undeveloped. Each cormidium 

 (fig. 6) is composed of four different organs, arising from a common pedicle, viz., (l) a 

 blue siphon, with black hepatic villi and a terminal mouth ; (2) a long blue tentacle (t) ; 

 (3) a light greenish spindle-shaped basal ampulla (to) arising from its base; and (4) a 

 small clustered monostylic gonodendron (g). The structure of all these parts is the 

 usual one, as described above (pp. 345-347). The second tentacle and ampulla (counting 

 from the apex) are far larger than those of the other cormidia. The size of this main 

 tentacle and of the appertaining central siphon was in a second specimen (bearing six 

 mature cormidia) comparatively much larger. 



