TWO NEW SPECIES OP THE PHOEONIDEA. 
261 
sections that the mesentery which attaches this extremity 
to the bend in the digestive tube during life was broken; 
consequently it seems probable that the pit which has been 
so often described is only caused by tension in this mesentery 
due to its contraction. A similar slight concavity is fre- 
quently seen in the body-wall at the insertion of the lateral 
mesenteries (Figs. 2 and 4, 1. mes.). 
The basement tissue (Figs. 2 and 5, h. t.) consists of a homo- 
g’eneoLis membrane without any cells such as have been 
observed in Phoronopsis harmeri, subsequently to be 
described. 
Muscular Layers. — The circular muscles seem to be as 
usual in other species of Phoronis, and the distal region of 
the body is traversed by numerous radial muscles (Figs. 2 
and 5, r. m.). 
The longitudinal muscles are greatly developed, and differ 
from those of all species so far described in the fascicles 
having a different character at different levels. In the distal 
region the fibres are arranged somewhat irregularly to form 
fascicles as described for Ph. hi ppocrepia, Ph. buskii 
(McIntosh [12]), Ph. australis (Benham [2]) (Fig. 2, Z. m.), 
whereas in the region of greatest development, i.e. about 
lium. (1. Diaphragm, d.a. Digestive areas of stomach, d.b.c. De- 
generating blood-corpuscles, ep. Epistonie. e. v. Efferent vessel. /. 
Nerve-fibrils. /. c. Fusiform corpuscles, /ol. Follicle cells of ova. </. 
Ganglionic mass. ff. <j. Epithelial glands with spherical granules, (jr. 
Groove in stomach. <jr. ii. Granular peritoneum, h. p. Hypertroj)hied 
peritoneum round afferent vessel, int. Intestine, i. t. Tentacle of 
inner series. 1. Lumen of affei’ent vessel. 1. m. Longitudinal muscle. 
1. mes. Lateral mesentery. 1. n. Lateral nerve. 1. o. Lophophoral organ. 
VI. (j. Mucous glands, in. mes. Median mesentery, n. Nuclei, n.d'. 
Nephridial duct. n.d. Terminal part of nephridial duct. n.f. Nephri- 
dial funnel. ?i. p. Nephridiopoi-e. n.?-. Neiwe-ilng. w. f. Nei-vous tissue. 
o. Ova. o’s. (Esophagus, o. <j. Oil-globules, o. t. Tentacle of outer 
series, p. Peritoneum, p. c. Posterior coelom, p. (j. Pigment-granules. 
p. gas. Pregasti-ic region of the digestive tube. pg. c. Pigment-bear- 
bearing corpuscles. pg. s. Perigastric sinus, r. Rectum, r. m. 
Radial muscles, st. Stomach, vp.t. Vaso-peritoneal tissue. ?/. Yolk- 
spherules. 
