NOTES AND QUERIES. 399 



AEACHNIDA. 



Same Species of Tick Infesting Polecat and Otter.— In an article 

 in ' The Field ' of July 29th, 1916, on the Polecat by Miss Frances 

 Pitt, I was interested to read that the tick found upon these animals 

 was the species Ixodes hexagonus, for curiously enough the same 

 species is sometimes found upon the Otter. On August 6th, 1910, I 

 took females of this species from the head of a dog Otter killed by 

 hounds near Lancaster, and although I have handled a fair number 

 of freshly-killed Otters at different times, this is the only one upon 

 which I noticed any parasites. As I am informed by Miss Pitt that 

 all the ticks found upon the Polecats were females, the same being the 

 case with all those taken from the Otter, it would be interesting to 

 learn where the males of this particular species are to be found. — 

 H. W. Eobinson, M.B.O.U., F.Z.S.Scot. (Caton, Lancaster). 



ECHINOIDEA. 

 A Mode of Feeding in a Sea-Urchin. — On p. 98 of the present 

 volume of ' The Zoologist ' it was pointed out that a captive Purple- 

 tipped Sea-Urchin had been observed to wrap a long Sabella around 

 its body in such a way that the echinoderm was able to feed easily 

 upon its inconveniently long victim. During a vacation dredging 

 expedition at Walton-on-the-Naze (Essex) on June 29th I obtained 

 a number of fine examples of this species of Sea-Urchin. One of 

 these animals, which was about 40 mm. in diameter (including the 

 spines), carried a Sabella wrapped tightly around its body. The 

 worm lay at right angles to the equator of the echinoderm, and one 

 end of the tube of the Sabella was found actually within the grasp of 

 the Sea- Urchin's teeth when the echinoid was lifted out of the dredge. 

 This observation upon a free Sea-Urchin affords welcome confirma- 

 tion of those previously made only upon captive individuals. — H. N. 



MlLLIGAN. 



Rate of Growth of Echinus miliaris. — A Purple-tipped Sea-Urchin 

 {Echinus miliaris) lived for 436 days in an aquarium. When the 

 animal was captured its long diameter (excluding the spines) was 

 27 mm., and at the time of its death this diameter had increased to 

 30 mm. The growth in diameter of the Sea-Urchin had therefore 

 been at the rate of 1 mm. in every 145'3 days. Of course, the rate 

 of growth of a marine animal in captivity may be quite different 

 from that of the same animal in the sea, but so little is known upon 

 the subject that any facts which bear upon it will be useful. — 

 H. N. MlLLIGAN. 



