336 
THE VOYAGE OF H.M.S. CHALLENGER. 
The posterior processes of the maxillge are short and broad, the two almost forming a 
semicircle. The anatomy of the body -wall agrees with that in the ordinary form. 
Hyalinoecia tuhicola, 0. F. Muller, var. (PI. XL. fig. 1). 
Habitat . — Trawled in great numbers at Station 320 (off the coast of Buenos Ayres, 
South America, to the south of the estuary of the Eio de la Plata), February 14, 
1876; lat. 37° 17' S., long. 53° 52' W.; depth, 600 fathoms; bottom temperature 
37° ‘2, surface temperature 6 7° ‘5 ; sea-bottom, green sand. It is stated on the label that 
the specimens came from hard ground, but this is unusual. 
Fig. 88.— Maxillae and dental plates of Hyalinoecia tuhicola, 0. F. Muller, var. ; x 15 diameters. 
Fig. 89. — Mandibles of the same ; x 15 diameters. 
This large Annelid inhabits a tube about the size of a goose-quill, but much resembles 
the ordinary form in appearance, both in regard to animal and tube. The latter 
measures from 200 to 220 mm. in length, with a diameter at the wide end of 8 mm., 
and at the narrow extremity of 4 mm. 
The head agrees with that of the typical form except in size and in the variable 
proportions of the organs. The eyes are absent. The dental armature (Figs. 88, 89) 
differs from the description of Elders in having fourteen teeth on the right great dental 
plate and, seventeen on the left, being one more on each side, but the difference in size is 
striking. Moreover, the number of teeth is variable, and occasionally it corresponds with 
that in the typical examples. 
