742 



6^8-^ " THETIS " SCIKNTIFIC RESULTS. 



specimen is similar, but the supernumerary arms are rather 

 smaller ; a third specimen is similar, but the supernumerary 

 arms are longer, reaching 20 mm., and there are a few small, 

 slender and weak cirri, each with 12 segments. 



The arm length is 70 mm. 



Localities. — Holothuria Bank, 38 fathoms : — Three specimens. 

 Baudin Island, North-western Australia : — One specimen, resem- 

 bling the third mentioned above from Holothuria Bank. All 

 the specimens are in the British Museum, and are described 

 herein with tlie kind consent of "Professor F, J Bell. 



Remarks.— Thifi is a most extraordinary species, appearing 

 partially to bridge the gap between the ten-armed forms, Comatula 

 pectinata, G. Solaris, C purpiorea, and C. micraster, and the 

 twer)ty-armed C. rotaJaria. 



Some time ago, basing \i\y conclusions upon a study of the 

 aim structure, I ventured the rematk that in compound arm 

 division the inner arms are phylogenetically the oldest ; the 

 truth of this statement is strikingly illustrated hy the present 

 species in which we find the original arms of the ten-armed 

 stage, next to them young arms less than half as large, and 

 exteriorly pinnules which have not yet become replaced by arms. 



COMATULA BRACHIOLATA (Lamarck). 



Comatula hracltiolata, 1816, Lamarck, Hist. nat. des animaux 



sans vertebres, vol. 2, p. 535 (? Atlantic Ocean). 

 Alecto rosea, 1841, J. Miiller, Archiv. fiir Naturgesch., 1841, i., 



p. 143 (unknown locality). 

 Actinometra hrachiolata, 1888, P. H. Carpenter, "Challenger" 

 Reports, Zool., vol. 26, p. 380 {Australia). 1891, Hartlaub, 

 Nova Acta Acad. vol. 58, No. 1, p. 107 {Australia). 

 Differential Characters. — This is an exceptionally rugged s[)ecies 

 with a large broad centrodorsal and short stout tuberculous arms. 

 The very numerous cirrus segments, all of which are subequal and 

 much broader than long, serve to distinguish it at once from all 

 the other species of the genus. 



Nothing is known in regard to its distribution ; the two 

 specimens upon which Miiller's Alecto rosea is based, and which 

 are now before me, are supposed to have come from Australia. 



Hetnarks. — I have examined the types both of Lamarck's 

 Comatula hrachiolata (at Paris), and of Miiller's Alecto rosea (.sent 

 to me from Berlin), and I find them to be specimens of the same 

 species. A beautiful specimen in the British Museum was 

 taken at Port Phillip, and I have seen others from the vicinity 

 of King George Sound. It is evident, therefore, that this is a 

 South Australian species like Comanthus trichoptera. 



