GASTEROPODA. PECTINIBRANCHIATAi 



ovate, the outer lip thin ; the colour white, with two rows of 

 red spots on the whorls, and a third on the last, or the spots 

 of the two anterior rows of the last whorl united into one hand. 

 Length an eighth of an inch, breadth rather more than half 

 the length. 



Distinguished from Rissoa interrupta by its broader form, 

 spiral striae, and more convex whorls. 



Found by me among shell sand between the Dee and the Don. 



Turbo semistriatus. Mont. Test. Brit. Suppl. 136. — Cingula 

 semistriata. Flem. Brit. Anim. 309. — Rissoa sernistriata* Jolmst. 

 Benv. Tr. iii. 271. 



7. Rissoa interrupta. Spot-banded Rissoa. 



Shell ovato-conical, pellucid, smooth, glossy; the spire a 

 little shorter than the last turn, directly tapering to an obtuse 

 point ; the whorls five flattish, the suture distinct ; the aperture 

 roundish or very broadly ovate, the outer lip rather thin ; the 

 colour white, with the apex purplish, a spiral series of reddish- 

 brown oblong spots near the upper margin of each whorl, and 

 a band on the last. Length one-eighth of an inch, breadth 

 half the length. 



It varies in colour, being sometimes brown with a white 

 spiral band. 



Common on the rocky coasts between tide-marks. Frequent 

 among shell sand between the Dee and the Don ; also in Cru- 

 den Bay. 



Turbo interruptus. Mont. Test. Brit. 329. PI. 20. f. 8.— Cingula 

 interrupta. Flem. Brit. Anim. 271. — Rissoa interrupta. Johnst. 

 Berw. Tr. iii. 271. 



8. Rissoa reticulata. Reticulated Rissoa. 



Shell ovato-turrite, rather thick, pellucid, white ; of five 

 rounded volutions, strongly reticulated with numerous longi- 

 tudinal and transverse ridges, the last turn with only spiral 

 ridges anteriorly ; the suture distinct ; the aperture roundish, 

 the outer lip thickened externally by a convex reticulated rib, 

 the inner reflexed on the columella, leaving a small groove 

 behind. Length nearly a twelfth of an inch, breadth rather 

 more than half the length. 



When long dead the shell is thicker, opaque, and brownish 

 or dull white ; or, among sand, thinner, more transparent, and 

 hyaline-white. I have seen it transparent, yellowish, with the 

 spiral ridges brown. 



First found by Miss Isabella Macgillivray, in October, 1812, 



