120 W. F. R. WELDON. 



dicated is exactly furnished by the Rhabdocoel pharynx 

 (fig. 16). 



We seem, therefore, to have in Dinophilus a form which, 

 related on the one hand to the Archiannelids, retains on the 

 other many features characteristic of the ancestor common to 

 those groups (especially Chsetopods, Gephyreans, Mollusca, 

 Rotifers, and Crustacea) which possess a more or less modified 

 trochosphere larva ; and of these the relations of the body cavity, 

 of the excretory system, and of the pharynx, seem to point 

 unmistakeably to a Turbellarian origin. 



EXPLANATION OF PLATE X, 



Illustrating Mr. W. F. R. Weldon's Paper on a " Species of 

 Dinophilus Gigas.^' 



List of Reference Letters, 

 an. Anus. c. p. Cephalic ciliated pits. ci. Transverse ciliated bands. 

 E. Eye. e. gl. Gland cells of lips. gr. Granular cells of ectoderm, h. ph. 

 Horizontal diverticulum of pharynx. In. Intestine. /. m. Longitudinal muscle- 

 fibres. M. Mouth, m. ]}h. Muscular appendix of pharynx, vi. ep. Myo- 

 epithelial cells of ectoderm. Me. Median lobe of gonad, ne. Position of 

 observed nephridia. n.f. Nerve-fibres. n. g. Nerve-cells, n. I. Lateral 

 nerve-cord. oe. (Esophagus, r. m. Circular muscles, st. Stomach, s. h. 

 Cephalic sense hairs, sh^. Post-cephalic rings of sense hairs, ce. Deep cells 

 of cephalic ectoderm. Br. Brain. St. Stomodseal musculature. 



Figs. 1 — 10. — Dinophilus gigas. 



Fig. 1. The live animul extended, seen by transmitted light. 



Fig. 2. A specimen contracted by treatment with corrosive sublimate 



solution, but not otherwise distorted. This figure shows fairly well the 



shape assumed on irritation by the live creature. 

 Fig, 3. A transverse section through the prse-oral lobe. 

 Figs. 4 — fi. Transverse sections through the pharyngeal region. 



