4 BOTRYLLIDiK. 



Oeniis DIDEMlVIlJiTI, Savigny. 1827. 



Test coriaceous, polymorphous, sessile, and incrusting ; systems 

 numerous, compressed, without central cavities or distinct circum- 

 scription. Individuals scattered ; abdomen pedunculate. Ovary 

 placed by the side of the intestinal loop, increasing in length when 

 the eggs are fully developed. 



The Tunicaries composing the systems of individuals in this genus 

 are without any appreciable order of arrangement, and are scattered 

 over the common body. 



Didemnium roseum. 



Didemnium roseum, Savigny, &c., Saks, Reise i Lofoten eg Finmarken, p. 33, 1850. — 

 Packard, Inv. ofLabr. in Mem. Bost. Soc. N. H. i. 27.5 (1867). 



Colony forming a calcareous, thin, incrusting mass, coriaceous, 

 much expanded, surface finely granulated, being covered densely 

 with round mammillated bodies. Branchial orifices rudely arranged 

 in quincunces, slightly raised above the surface, formed of six trian- 

 gular lobes, with the alternating lobes a little unequal in size, com- 

 posed of three or four granules a little larger than those on the sur- 

 face generally. 



It beai's a close resemblance to Didemnium exaratum, Grube 

 (Ausflug nacli Trieste, Taf. ii. Fig. 2, 2 a), but the branchial o])en- 

 ings are thicker, and the mass thinner and more calcareous in our 

 species. It agrees exactly with Sars's description of D. roseum, 

 though it is whitish in alcoholic specimens. 



Found frequently incrusting fucoids in masses an inch in diam- 

 eter, in ten fathoms, Hopedale ; and on the whole coast. I have 

 also dredged it at Eastport in twenty fathoms. (^Packard.') 



I can add no further information in regard to this species than 

 that contained in Dr. Packard's description copied above. 



Family SALPID^. 



Animal free, pelagian, in the form of a more or less cylindrical 

 tube open at one or both ends ; test and mantle continuous with 

 one another at the respiratory apertures, but elsewhere separated 

 by a wide space ; gill forming a liollow band crossing the respira- 



