TUNICATA 665 



Key to the species of Molgula here described: 



G! Siphons contiguous at the base. 



b t Siphons not swollen at the base M. MANHATTENSIS 



6, Siphons swollen at the base M. PELLUCIDA 



a. Siphons not contiguous. 



&! Siphons short M. ARENATA 



& a 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 

 in shallow water; in Long Island and Vineyard Sounds, manhatiensis 



M. pellucida Verrill. Body globose, with a smooth, (Verriii). 

 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 in 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 water. 



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

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

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

 from Vineyard Sound northwards, in mud or fine sand, 

 where it is locomotory; often abundant. 



3. BOSTRICHOBRANCHUS Traustedt. Like Eugyra but 

 with corkscrew-shaped infundibula in the meshes of the 

 branchial sac : 2 species. 



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 the 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. 



