249 
than the two above. One of these is the Palmipes lobianci Ludw., 
which represents, according to Ludwig, most probably a hybrid 
between Palmipes membranaceus and Asterina gibbosa"). The other 
case is mentioned by Verrill (Op. cit. p. 544), who reports the 
rather common occurrence at Sitka a. 0. places on the North 
American West Coast of hybrids between Asterias epichlora (Br.) 
and Pisaster ochraceus (Br.), the former being a small, usually 
six-rayed, diplacanthid species, the latter a large, coarse, five-rayed, 
monacanthid species. Verrill also suggest the existence of hybrids 
between AÅsterias epichlora and A. hexactis (St.), and of either of 
these species with Aszerias Troscheli (St.). It would then appear 
that this region is unusually favourable for the study of hybridism. 
NR Leltbig. Die Seesterne des Mittelmeeres. Fauna u. Flora d. 
Golfes v. Neapel. 24. Monogr. 1897. p. 267. Professor Ludwig has 
kindly called my attention to this form, which I had forgotten. 
Explanation of Plate IV. 
Fig. 1. Asterias rubens L. Abnormal specimen from the Isefjord. 
— 2. Asterias Miilleri var. gronlandica Stp. Abnormal specimen from 
Greenland. 
— 3. Astropecten irregularis (Penn.). Abnormal specimen from the 
coast of Bohuslån. 
— 4. Ceramaster (Pentagonaster) granularis (Retz.). Abnormal spec- 
imens from the Trondhjemsfjord. 
— 5, Ophiura (Ophioglypha) orn Ltk. Abnormal specimen from the 
, Northern Stråmfjord, Gre 
— 6. Ovhiura Geil ) SL Nbelel. Abnormal specimen from 
the northern Kat 
All the figures are mme in natural size. 
22,—5.—1918: 
