148 CEYLON PEARL OYSTER REPORT. 



between the termination of the gonads and the circular canal, has a strong tendency 

 to curve and to send out lateral branches, which occasionally unite with lateral 

 branches from an adjacent canal, or the union of two or three canals may occur, so 

 that just near the margin of the umbrella the radial canal system appears to be very 

 irregular. 



The gonads are situated upon the radial canals and extend almost from the stomach 

 to within a short distance of the circular canal, the distance from the termination 

 ot the gonad to the circular canal being about 2 millims. to 3 millims. The gonads 

 are arranged in a lateral band along each side of the radial canals. At first a radial 

 canal is merely a narrow, slender, inconspicuous tube (fig. 14, B.), then when the gonads 

 begin to develop, the wall of the canal becomes thicker and increases in size. In this 

 specimen the gonads are much larger than in the Maldive specimens. They have the 

 appearance of cylindrical sacs, about 6 millims. in length and 1 millim. in diameter, 

 with the wall slightby crumbled. Between the canals bearing the fully-developed 

 gonads there are, here and there, canals which are of much later growth showing 

 gonads in various stages of development. Some of these canals are at about the same 

 stage as those in the Maldive specimens, showing that the Maldive specimens had 

 not reached their full development. 



The tentacles (fig. 12) belong to the same type as those of the Maldive specimens, 

 but the basal bulbs have not such a long lateral extension along 1 the margin of the 

 umbrella. I have again examined the tentacles of the Maldive specimens, and find 

 the extension along the margin to be slightly variable. The tentacles are also much 

 longer and larger than those in the Maldive specimens, but they have the nemato- 

 cysts arranged in the same manner. The nematocysts are in large clusters, which are 

 laterally situated, on both sides, along the whole of the tentacle (fig. 13). 



The marginal bulbs, like the basal bulb, at first sight, as shown by the figures in 

 this Report and in the Maldive Report, do not appear to be similar, but I believe 

 that the difference in general appearance is due to a lateral contraction of the margin 

 of the umbrella of the specimen in this collection. The bulbs are closely packed 

 together, touching one another, and the sense-organs are squeezed out on to the 

 inner margin of the umbrella (fig. 15). This lateral contraction would also explain 

 the shortness of the basal bulbs of the tentacles upon the margin. In the genus 

 JEquorea, excretory pores are present upon the inner side of the circular canals, one 

 opposite each tentacle or bulb. In my description of this species in the Maldive 

 Report I did not mention the excretory pores, for the simple reason that I could not 

 see any. But I have now cut a series of sections of a marginal bulb and found the 

 pore in the usual place just above the velum. There is no trace of any external 

 papilla or swelling, but simply a slender, narrow tube running from the circular canal 

 to the exterior. It is just like a slit in the wall of the circular canal. 



The sense-organs (fig. 15) are on the inner side of the margin of the umbrella, and 

 are arranged in groups These groups are placed midway between the marginal 



