OCR Text |
Show 1904.] MARINE FAUNA OF ZANZIBAR. 321 others, the posterior left crescentic plate lies alongside and approximates to the size and shape of the great dental. The numbers of the teeth are fairly large, they being especially small and numerous on the crescentic plates. The following formula? <iive their variation :- 9- 9 : 10- 8 : 9-11 : 11-11 : ? + 7- ? 8 + 9-13 11 + 10-13 ? + 9- I The asymmetry of the great dentals exists even when the numbers of the teeth they bear are the same, as was the case in the specimen from which text-fig. 63 was prepared. The lower jaws are almost entirely calcareous in composition and their end-plates are indented. Text-fie-. 63. Upper jaws of a full-grown specimen of E. indica. Left anterior plates moved upwards from the natural position. The feet are comparatively long and slender with long seta;, and are well separated from each other. The dorsal and ventral cirri are well developed, but not annulated. Large gills cover PROC. ZOOL. Soc-1904, VOL. I. No. XXI. 21 |