MOLGULA MANHATTENSIS. 167 



the hijpophysis, a tube connecting the subneural gland with the 

 oral cavity. 



5. A ring of oral tentacles will be seen in the mouth, anterior 

 to the peri-pharyngeal bands. Of what use are sensory tentacles 

 in the mouth? How many tentacles are there? 



6. The very short esophagus opens into the stomach, which 

 will be recognized by the brown digestive glands that cover 

 it. From the stomach the intestine forms a loop on the left 

 side, and is easily traced to the anus, which opens dorsal to the 

 pharynx in the atrial chamber. A longitudinal fold, the hjph- 

 losole, extends throughout the intestine. What is the use of 

 such a fold ? 



Reproductive System.— On each side of the body, adherent to 

 the inside of the mantle, is an elongate hermaphrodite gland. 

 Each gland consists of a lighter part, the testis, and a darker part, 

 the ovary. The gonoducts open on the outer wall of the atrial 

 cavity near the base of the atrial siphon. Each consists of two 

 ducts, oviduct and vas deferens. Microscopic examination of 

 the oviduct may show the presence of eggs. 



Excretory System. — The renal organ is a conspicuous, elon- 

 gated sac on the right side. It contains a brownish fluid and 

 usually some solid matter. It does not possess a duct. 



Nervous System.— The cerebral ganglion, which in Molgula is 

 almost completely surrounded by the subneural gland, lies close 

 to the mantle, between the two siphons, and is thus dorsal to 

 the mouth. Nerves can be seen passing from the ganglion to 

 the two siphons. The hypophysis, a tube leading from the sub- 

 neural gland, opens as the dorsal tubercle above mentioned. 



Circulatory System.— 1. The heart, which lies on the right 

 side between the hermaphrodite gland and the renal organ, is 

 inclosed within a pericardium which is a portion of the coelom. 

 It should be studied in a living specimen, with the aid of a hand- 

 lens. 



2. If a very small Molgula (one-eighth of an inch in length) 

 is studied alive in a watch-glass with the microscope, the course 



