228 



RITTER 



MEASUREMENTS OF SOME OF THE LARGER SPECIMENS. 



Test of moderate thickness, containing a network of vessels and 

 many large vesicular cells. Mantle nowhere highly developed, but 

 particularly thin on side of attachment where the muscle fibers are al- 

 most entirely wanting. Muscle fibers of mantle not disposed in any 

 definite bundles, but spread out in a uniform sheet and running in all 

 directions. 



Branchial apparatus. — (Siphons described above.) Branchial 

 tentacles variable in number, even in the same cluster of individuals ; 

 thirty-five or more in the larger specimens. 



Hypophysis mouth rather large, horseshoe-shaped, about as broad 

 as long, limbs incurved somewhat but not produced into spirals, open- 

 ing nearly directly forward. Ganglion and gland close together, 

 forming an elongated mass, lying not far behind the hypophysis (p1. 

 XXVII, fig. 4). 



Dorsal lamina a rather broad membrane provided with transverse 

 ribs which project somewhat beyond the free edge of the membrane. 

 No serrations of the edge in addition to these projecting ribs (p1. xxvii, 

 fig- 4) • Lamina extending for some distance behind the esophagal 

 opening, on the right side. 



Folding of the branchial sac not deep, but distinct. Internal longi- 

 tudmal vessels bearing prominent, though simple, papillae placed at 

 the points of crossing of the transverse vessels ; intermediate papillae 

 also frequently present, /. c, papillge in the intervals between the 

 transverse vessels. Usually about two folds of the sac and about ten 

 stigmata between each two longitudinal vessels. 



Digestive apparatus. — Mouth of the esophagus far back, though 

 anterior to the posterior end of the dorsal lamina. Stomach rather 

 prominent, cask-shaped, little longer than broad ; wall with about six 

 distmct, regular, longitudinal folds on its outer half. Loop of intes- 

 tme long, reaching more than two-thirds of the way to the anterior end 



