338 
THE VOYAGE OF H.M.S. CHALLENGER. 
The tubes are proportionally less tapered, rougher in their structure, and in addition 
have numerous adventitious growths, e.g., Mollusca, Molluscoida, and Serpulce. 
This variety for the most part corresponds in transverse section with the typical form, 
the two dorsal blood-vessels, the nerve-area, and other parts being well marked, the latter 
(nerve-area) is, however, less free than in Hyalincecia tubicola, for the upper oblique and 
vertical fibres shut in the region at intervals. The great glandular organ at the outer 
border of the ventral longitudinal muscles is largely developed. 
Grube ^ describes a form [Hyalincecia platyhrancliis) from the Cape Verde Islands, 
in which the flattened branchiae commence on the eighteenth 
segment. It seems to be closely allied to the foregoing. 
A still more marked variety was dredged on the 12th 
February 1873, off Gomera, Canary Islands, in 600 fathoms. 
In this the long branchiae commence on the twentieth 
foot (instead of the twenty-fourth in the typical form), and 
both they and the dorsal cirri are much longer than those of the 
previous examples. 
The maxillae (Fig. 90) are powerful and slightly hooked. 
The left great dental plate shows fourteen teeth, the right 
twelve ; the left lateral paired plate had several broken teeth, 
but apparently from six to nine ; unpaired left twelve ; right 
lateral ten distinct and several crenations. A quadrangular 
accessory plate with a conical internal tooth. The mandibles 
Fig. 90. — Left maxilla of Hyalincecia 
Micoia o. F. M., var. longi- pointed extemally, and are separate. 
oranchiata ; enlarged. ^ ■*- 
No eyes are present. The tips of the posterior hooks have 
thicker and stronger forks than in. the typical form. 
The vertical and oblique muscles in the example from Gomera are less conspicuous, 
otherwise the structure is typical, though the branches of the blood-vessels are 
numerous. 
The Hyalincecia camiguina of Grube,^ from the Philippines, is another form which 
approaches the typical one closely, differing chiefly in the origin of the branchiae and the 
serrations of the dental plates. 
1 Monatsher. d. k, preuss. Akad. d. TViss. Berlin, 1877, p. 527 ; and Jahrh. schles. Gesellsch., June 1877, p. 12 (sep. 
Abd.). 
2 Annelidenfauna d. Philippinen, p. 142, Taf. x. fig. 1. 
