370 Ortmann — Invertebrate Fossils from Patagonia. 



upon shells, stones, etc. Outer surface transversely rugose. 

 Diameter, 3 mm . 

 San Julian. 



5. Terebella magna sp. nov. Large cylindrical tubes, iso- 

 lated or growing in groups of two or three, straight or slightly 

 curved. Walls composed of large and irregular fragments of 

 shells. Inner surface of tubes smooth, outer surface very 

 rough. Diameter of inner tube, 12-15 mm . 



Systematic position of these tubes, apparently built by a 

 worm, doubtful. 

 San Julian. 



Brtozoa. 



6. Melicerita tr if oris sp. nov. Zoarium foliaceous, lobate. 

 Zooecia hexagonal, disposed quincuncially on both surfaces of 

 the zoarium. Orifice crescentic, large, about in the middle of 

 each cell. Besides there is an ovarian opening on the summit 

 of the cell, and two (? avicularian) openings on the side of the 

 mouth. 



The three openings in the upper part of the cell distinguish 

 this species from all the rest. 

 Upper Rio Chalia. 



7. Heticulijpora jpatagonica sp. nov. Closely resembling 

 JR. transennata Waters (Quart. Journ. Geol. Soc, vol. xl, 

 1884, p. 689), and differing only, if at all, in the branches of 

 the zoarium being a little stronger, and the zooecial openings 

 being more crowded. 



Santa Cruz. 



8. Tennysonia siibcylindrica sp. nov. Closely resembling 

 the only known species of the genus, T. steUata Busk (Cat. 

 Mar. Pol. Brit. Mus., 3, 1875, p. 31), but differing by the more 

 slender branches of the Zoarium, which are subcylindrical, and 

 the slightly prominent orifices of the cells. 



Santa Cruz. 



Pelecypoda. 



9. Modiola andina sp. nov. Shell small, elongated. Apex 

 near anterior end. Both valves convex, with a blunt ridge 

 running down from the apex to the posterior and inferior end. 

 This ridge is slightly curved, concave toward the lower margin. 

 Upper margin almost straight in its anterior part, forming a 

 blunt angle with the straight posterior part, which passes in a 

 regular curve into the posterior margin. Yentral margin con- 

 cave. Surface of shell in the upper half (above the oblique 

 ridge) finely radially striated. Lower part of surface smooth, 

 only near the anterior end, below the apex, with a few fine 

 striae. Length of shell, 24 mm ; height, 9 mm . 



Lake Pueyrredon. 



