MEDUS.E. 165 



Abyla Leuckartii Huxley. 



Abyla Leuckartii Huxley, T. H., 1859 ; Oceanic Hydrozoa, p. 49, PI. III., Figs. 2-2". 



Two specimens of this Siphonophore were obtained by the " Albatross," 

 one in the Marquesas, and the other about 100 miles north of the Paumotus 

 Islands. Huxley found it off the east coast of Australia. The smaller of 

 our specimens is well represented by Huxley's Figure 2 ; in the larger, 

 however, the anterior nectophore is 22 mm. in length and has the shape of a 

 narrow, elongate, five-sided pyramid ; the apex of which is sharp and pointed. 

 It is much flattened laterally in the plane passing through the axes of the 

 phyllocyst, hydroecium, and bell-cavity. The cavity of the anterior swim- 

 ming-bell is long and tapers to a point very near the apex of the bell. 

 There are four radial canals and a simple circular vessel, and these are put 

 into connection with the gastro-vascular cavity of the hydrosoma by means 

 of a short, straight duct, which reaches the side of the bell-cavity at about 

 its middle point. The velum is well developed and is provided with 

 powerful muscles by the rapid contraction of which the animal is en- 

 abled to dart through the water. A deep, funnel-shaped hydroecium 

 is situated midway between the bell-cavity and the phyllocyst. The hy- 

 drosoma arises from the inner apex of this cavity. In both Huxley's 

 and our specimens there were but two well developed polypites, but there 

 were several other smaller ones, probably in course of development. The 

 largest polypite is terminal and a cluster of small or undeveloped tentacles 

 arises from the side of its proximal end. Among these tentacles there is 

 one which is much longer than the rest, and this one terminates in a coiled, 

 helical, nematocyst battery. The nematocyst batteries of the short tenta- 

 cles, however, are straight and finger shaped. Close to the proximal end 

 of the hydrosoma there is a cluster of small immature polypites and among 

 them a single small, auxiliary swimming-bell. No large inferior swimming- 

 bell existed either in Huxley's or in our specimens, and it is probable that 

 it had been lost through accident. The phyllocyst is large and cucumber 

 shaped, and is connected with the hydrosoma by means of a short, straight 

 duct. It lies imbedded in the gelatinous substance, and extends downward 

 parallel with the longitudinal axis of the animal. It is composed of large, 



