ORTMANN : TERTIARY INVERTEBRATES. 67 



Fam. ESCHARIDA1 Johnst. 



Gen. ASPIDOSTOMA Hcks. 



11. ASPIDOSTOMA GIGANTEUM (Busk). 



PI. XIII, Fig. 4. 



1854 Eschara gigantea Busk, Cat. mar. Polyz., Brit. Mus., v. 2, p. 91, pi. 



119, f. 3. 

 1 88 1 Aspidostoma crassum Hincks, in: Ann. Mag. Nat. Hist, ser. 5, v. 



7, p. 1 60, pi. 10, f. 6. 



1884 Aspid. giganteum Busk, Challenger Polyz., i, p. 161, pi. 33, f. 3. 

 1891 Eschara (Aspidostoma) gig. Jullien, in: Miss. Cap Horn, v. 6, p. 



77, pi. 6, f. 5-6. 

 1900 Asp. gig. Ortmann, in: Amer. Journ. Sci., v. 10, p. 378. 



Zoarium erect, compressed, bilaminate, contorted, divided and coales- 

 cent frequently. Zooecia arranged quincuncially, thick-walled, broadly 

 pyriform or hexagonal, divided by deep sutures, tumid in front, but de- 

 pressed in the center. Mouth at the summit of the depressed area, upper 

 lip arched, with an elevated hood rising into two prominent processes. 

 Lower lip with a broad plate covering the mouth ; margin of this plate 

 thickened, squarely truncated in front. Ocecia rounded or oval (Hincks 

 says, elongated), depressed in the older parts of the colony, more promi- 

 nent in the younger parts. 



Remarks: There is no doubt that this fossil form corresponds to the 

 living species. The most characteristic features are the hood-like (pent- 

 house-like, Busk), bifid projection of the upper lip of the mouth, the broad 

 plate of the lower lip, and the central depression of the cells. All these 

 characters are well exhibited in our specimens. The figures of Hincks 

 and Busk do not bring out these features very distinctly ; they are, how- 

 ever, better represented in Jullien's figures. 



Record of specimens : Mouth of Santa Cruz River; many fragments. 

 San Julian, Oven Point ; 2 basal parts of colonies. 



Distribution : Aspidostoma giganteum has been found so far only living 

 in southern Patagonia: Straits of Magellan, between Patagonia and the 

 Falkland Islands, and at Tristan da Cunha (110150 fath.). 



