TUNICATA 665 



Key to the species of Molgula here described: 



Oi Siphons contiguous at the base. 



fei Siphons not swollen at the base M. manhattensis 



62 Siphons swollen at the base M. pellucida 



02 Siphons not contiguous. 



61 Siphons short M. akexata 



62 Siphons long M. papillosa 



M. manhattensis (DeKay) (Fig. 1,007). Body globose or ovoid; 

 external surface corrugated, usually covered with foreign matter; 

 siphons contiguous; length 25 mm.: on rocks or eel grass, 

 often in clusters, in shallow water below low tide lines; 

 from North Carolina to Casco Bay; abundant. 



M. arenata Stimpson. Body globose, often com- 

 pressed, covered with sand which adheres tightly ; siphons 

 short, not contiguous; length 20 mm.: on sand and gravel Fig. 1,007 

 in shallow water; in Long Island and Vinej^ard Sounds. manhattensis 



M. pellucida Verrill. Body globose, with a smooth, 

 translucent tunic to which sand does not adhere ; siphons contiguous, 

 long and diverging and swollen at the base; length 25 mm.: on sand in 

 shallow water from North Carolina to Massachusetts Bay. 



M. papillosa Verr. Body globose, often compressed, covered with 

 sand or dirt; siphons not contiguous, long, and diverging; length 10 

 mm.: on sand and gravel m 10 to 20 fathoms; from Vineyard Sound 

 northwards; common towards the north. 



2. EuGYRA Alder and Hancock. Branchial sac without longitu- 

 dinal bars; a single hermaphroditic gonad present, which is on the left 

 in the bend of the intestine: 8 species; in shallow \vater. 



E. pilularis Verr. (Fig. 1,008). Body globose, covered with mud 



or fine sand; siphons close together, slender, and as long as the body 



^ oj when extended ; diameter up to 8 mm. : in 10 to 20 fathoms 



% g from Vineyard Sound northwards, in mud or fine sand, 



>;§-»&»,, where it is locomotory; often abundant. 



,•: ;:"v;''. ''^i 3. BosTRiCHOBRANCHTTS Traustedt. Like Eugyra but 



Xf^^v^^ with corkscrew-shaped infundibula in the meshes of the 



Fig. 1,008 branchial sac : 2 species. 



piiuiaria B. molguloides Metcalf. Body 3 cm. in diameter and 



not attached: Woods Hole; on muddy bottoms. 



4. Rhizomolgula Ritter. Body ovoid, prolonged posteriorly in a 



stalk which may be as long as or longer than the body and ends in a 



number of root-like branches; kidney and the single gonads on th^left 



side : 4 species ; in North Pacific and Atlantic Oceans. 



R. ritteri Hartmeyer. Body globose, wider than long, 8 mm. long 

 with a stalk of same length : Baffin Bay ; in shallow water. 



