228 BULLETIN OF THE BUREAU OF FISHERIES. 



Zoarium forming irregular, often radiate or catenulate colonies on shells, stones, and occasionally 

 on algae. Zooecia rather small, the basal portion solidly calcined or very finely punctate; membranous 

 area oval to elliptical, border slightly raised, smooth, or slightly granular, and usually studded with 

 sharp spines which bend over the area. In the more usual form of the colony there are 8 or 10 pairs 

 of these spines, one pair situated at the anterior end of the cell and directed somewhat forward, and 

 there is a single basal spine somewhat larger than the others; in the other form of the colony to which 

 the species owes its name the margin is unarmed except for the basal spine, which is much stouter but 

 not elongated. Avicularia and ovicells are wanting. In some of the older zooecia there is not infre- 

 quently found a secondary calcareous lamina partly closing the membranous area after the manner of 

 M. catenularia (Jameson). Abortive zooecia are not uncommon, and these are sometimes completely 

 closed over. 



Occurring with some frequency throughout the region, dredged in 2 to 19 fathoms. It is most 

 common in Vineyard Sound and Buzzards Bay on shells and stones, but I have noted it on algae, egg- 

 cases of skates, and on the carapaces of crabs and Limulus; No Mans Land in drift, Muskeget Channel, 

 Great Round Shoals, and Nantucket and Woods Hole harbors on piles. The Escharina lineata of Leidy 

 is certainly this species, judging by the figure he gives (pi. X, fig. 22). I am inclined to the belief also 

 that Verrill's reference to M. lineata belongs rather to monostachys, for the reasons that he places Leidy 's 

 reference in his synonymy, and that his remarks concerning the species refer rather to monostachys. 

 The latter, moreover, is common in the region dredged by Verrill, while lineata seems to be rare south of 

 Cape Cod. 



Membranipora pilosa (Linne). [PI. xxn, fig. 30, 3oa.] 



Linne 1766-68, p. 1301 (Flustra pilosa). 



Leidy 1855. p. 141. 



Packard 1867, p. 272. 



Verrill and Smith 1874, p. 712. 



Verrill 18790, p. 29 (Electra pilosa). 



\Vhiteaves 1901, p. 95 (Electra pilosa). 



Cornish 1907, p. 76. 



Zoarium encrusting algae, stones, and shells, usually in irregular patches. Zooecia large, the basal 

 portion large and coarsely punctate; membranous area usually regularly oval, sometimes elongated, 

 surrounded by a rather high, smooth border, from which project several (usually 7 or 9) stout curved 

 spines. The basal spine varies greatly in size, and seems to be very closely correlated with the character 

 of the substratum. On flat surfaces, as stones, shells, and the broader algae, this spine is scarcely longer 

 than the others, while on rounded surfaces, as the smaller algae, hydroid stems, etc., the spine may be 

 considerably longer than the whole zooecium and more or less horny. Intermediate forms are occa- 

 sionally found which connect the long-spined typical variety with the short-spined var. dentata (Solander). 



Very common throughout the region, from low tide to 17 fathoms; more common on the broader 

 algae and taken wherever these occur. 



Membranipora lineata (Linne). [PI. xxin, fig. 31, 3ia, 3ib, 3ic.] 



Linne 1766-68, p. noi (Flustra lineata). 



Dawson 1859, p. 256. 



Packard 1867, p. 272. 



Verrill 18790, p. 29. 



Whiteaves 1901, p. 96. 



Cornish 1907, p. 76. 



Zoarium encrusting shells, stones, and algae, forming small rounded patches. Zooecia of moderate 

 size, the aperture oval or more elongate, surrounded by a rather narrow raised margin, from which pro- 

 ject 4 to 6 pairs of spines. These spines are rather slender and pointed, the anterior one or two pairs 

 are bent forward somewhat, and the others are directed upward and curve somewhat over the aperture. 

 A moderate sized avicularium is occasionally present at the base of the zooecium; it is somewhat raised 

 and the beak is rather prominent. Ooecium large, smooth, and shining, with a raised rib crossing it trans- 



