REPORT ON THE TUNICATA. 77 



broken up into a system of branching : m « 1 anastomosing tuhes, which form the b:i 

 of the infundibula. Large square meshes are, however, marked out by the intersection 

 of wide horizontal membranes with the internal longitudinal bars, and each of these 

 meshes contains a number of infundibula. The internal longitudinal bars are prominent, 

 and are connected by wide horizontal membranes, from which, as well as from the bars, 

 other more delicate oblique membranes spring ; these run in all directions over the inner 

 face of the sac. The stigmata are long, coiled spirally, and crossed here and there by 

 delicate radiating tubes. 



The Dorsal Lamina is short, and quite plain, with no ribs nor teeth. 



The Tentacles are large and branched ; they are ten in number, with some additional 

 very small intermediate ones. 



Tlie Dorsal Tubercle is prominent, and is elongated antero-posteriorly ; both horns 

 are much coded, forming large spirals. 



This dark, rough, and irregular-looking species has a large part of the outer surface 

 covered with adhering sand, &c, but there are no hair-like processes upon the test. 

 Both apertures are rather irregular, but the four atrial lobes are tolerably well marked 

 (PI. V. fig. 4). The mantle, branchial sac, and tentacles are all of a dark green colour; 

 and the mantle and branchial sac are very thick and opaque. The siphons (PI. V. fig. 5) 

 are prominent and funnel-shaped, with their margins beautifully and distinctly lobed, 

 the branchial having six and the atrial four. The musculature is close but very fine, 

 and is quite different from the characteristic Molgulid arrangement. On the right 

 side the mantle as usual is thinner over the region of the renal organ, the outline of 

 which shows through (PI. V. fig. 5). 



The figure of the branchial sac (PI. V. fig. 7), though correct as to the form and 

 position of the parts, does not represent well the depth of the infundibula and the 

 thickness of the sac. The interstigmatic vessels are delicate, and are coded spirally, the 

 different turns of the spiral being frequently connected by fine radiating tubes. Delicate 

 oblique membranes (PI. V. fig. 7, o.m.) are present in considerable number, running 

 irregularly over the inner face of the infundibula, and attached to the network formed 

 by the broken up transverse vessels. 



The dorsal tubercle is large and prominent. It lies in a shallow triangular peri- 

 tubercular area (PI. V. fig. 6), but extends nearly up to the tentacular circlet. 



The genital gland on the right side, placed anteriorly to the renal sac, is large and 

 flask-shaped, having a short wide duct attached at its upper end. The mouth of the 

 duct has its margin cut up into several long delicate finger-like processes. 



Two specimens, adhering together, were obtained at the Falkland Islands from 

 Station 315, January 27, 1876 ; lat. 51° 40' S., long. 57° 50' W. ; depth, 5 to 12 

 fathoms ; sand and gravel. 



