284 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.43. 



Tickle, Labrador, several colonies; off Beachy Island, between Flint 

 Island and Cape Mugford, Labrador, a few colonies representing tbe 

 nominal variety rostrata; outside of Hebron, Labrador, several 

 colonies. 



This is the species commonly known as Porella elegantula. It is not 

 the species described by d'Orbigny under that name, however, accord- 

 ing to Waters (1900, p. 81) who examined the type-specimen of ele- 

 gantula in Paris. Busk's name, saccata, therefore becomes the proper 

 name for this species. The Porella elegantula of d'Orbigny (1851 

 p. 102) is an unrecognized species from Newfoundland, unless, as 

 Waters (1900, p. 81) points out, P. perpusilla (Busk) should prove to 

 be a s3nQonym. 



PORELLA PERPUSILLA (Busk). 

 Plate 34, figs. 5, 5a, and 56. 

 Eschara perpusilla Busk, 1881, p. 236, pi. 13. 



Locality. — Outside of Hebron, Labrador, at 80 fathoms on gravel 

 bottom, one specimen about three-fourths of an inch in height. The 

 species has not been recorded since Busk described it. 



•The single specimen taken by Doctor Bryant agrees in all essentials 

 with the description given by Busk. As the species has not hereto- 

 fore been recorded in American waters, I quote Busk's description in 

 a somewhat abbreviated form. 



Zoarium diminutive, constituted of irregularly forked branches. Stem and lower 

 part of branches cylindrical, toward the ends flattened. Zocecia fusiform elongate, 

 mouth horizontal, anterior lip tridentate, the median denticle wide and expanding, 

 the lateral pointed, conical; immediately in front of the median denticle an avicula- 

 rium about half the length of the zocecium, with a circular mandible. At first sight 

 this form might be regarded as a very dwarf variety of E. elegantula. The characters 

 by which E. perpusilla may be recognized are: 



1. The smaller size of the zoarium, which probably does not exceed an inch in 

 height, and the cylindrical form, for the most part, of the stem and branches. 



2. The smaller dimensions of the avicularium and more especially of its mandible. 



3. The tripartite dentition of the anterior or inferior lip. 



4. The immersion of the mouth and of the orifice of the avicularium in the older 

 stages of growth, these parts in the stem and lower part of the branches being entirely 

 overgrown and obliterated. 



The median denticle is developed below the oral avicularium in 

 the same manner as that of P. concinna, while the lateral denticles 

 are merely lappet-like folds of the peristome. The species is evi- 

 dently related to P. saccata, but is sufficiently different to rank as a 

 distinct species. It was originally recorded from the Arctic Sea at 

 13 to 15 fathoms, Franklin-Pierce Bay and Smiths Sound. 



The species should be carefully compared with the type of d'Or- 

 bigny's elegantula, which also has rounded branches, but imtil this is 

 done it is better to record the species as above. 



