260 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



of gelatinous tissue extends forward, making up the great bulk of 

 the 8ul)staTice of the head. Even near the tip of the snout the 

 muscular layers are thin in comparison with this tissue. In the 

 region of the brain (PI. 19, fig. 119) this mass of tissue is many 

 times as thick as the muscular layers. To be sure, a very few 

 muscular strands pass diagonally across the tissue fi-om one side of 

 the head to the other, but the great bulk of its substance con- 

 sists of a jelly-like matrix with a few small nuclei and a small number 

 of strands of fibrous connective tissue. 



The elements making up this parenchyma are similar to those 

 which Montgomery ('97, pp. 1-37) has so fully described for 

 Cerebratulus and other genera. Many of the cells of this tissue 

 possess small oval nuclei and send out irregularly branching proc- 

 esses (PI. 20, fig. 124) in all directions. These branching cells 

 ramify through the gelatinous substance in which they are suspended, 

 and their processes often unite into an irregular network, as Mont- 

 gomery has described. The cell bodies are commonly filled with 

 vacuoles and granules of irregular sizes. The protoplasmic boimd- 

 aries are often so faintly marked that it is impossible to determine 

 the exact extent of the cell body. A number of these cells taken 

 from a section through tlie region of the brain are shown in PI. 20, 

 fig. 124. These illustrate the great variety of form exhibited by the 

 ordinary parenchyma cells of tlie gelatinous tissue. 



Proboscis not present in the preserved specimen, so that nothing 

 is known of its structure. 



Cephalic glands. — A very large cluster of cephalic glands lies 

 directly dorsal to the proboscis opening, and smaller clusters lie on 

 each side. They are all limited to the tip of the snout, however, 

 and extend posteriorly scarcely more than six to eight sections. 



Suhmuscular c/kmds. — These are also highly developed, and are 

 thickly packed in among and beneath the clusters of fibers in the 

 longitudinal muscular layer. The abundance of these glands in the 

 cephalic portion of the body is remarkable, and in certain regions 

 they form a layer more than equal in bulk to the longitudinal mus- 

 cular layer. In PI. 20, fig. 123, the relation of the glands to the 

 muscle bundles is shown. Tliis section was taken from the brain 

 region, and shows a greater mass of glands than of muscle fibers. 

 The ducts of the glands pierce the circular muscular and basement 

 layers to open through the integument to the surface of the body as 

 usual. 



