A.V. SYSOEV 



Table 1 Stations of H.E.M.S. 'Mabahiss' where deep-sea conoideans were collected. 



No. 



Position 







Area 



Date 



Depth, m 



Gear 



26 



12°29'30"N, 



50°51'30' 



E 



Gulf of Aden 



11.10.1933 



2312 



AT 



33 



13°41'00"N, 

 13°40'00"N, 



48°17'00' 

 48°18'00' 



Eto 

 E 



Gulf of Aden 



15.10.1933 



1295 



AT 



34 



13°05'36"N, 



46°24'42' 



E 



Gulf of Aden 



16.10.1933 



1022 



AT 



35 



13°14'24"N, 

 13°13'24"N, 



46° 14' 12' 

 46°10'00' 



Eto 

 E 



Gulf of Aden 



16.10.1933 



457-549 



OT 



42 



17°26'00"N, 



55°49'00' 



E 



Hadramaut 



27.10.1933 



1415 



TD 



62 



22°53'30" N, 

 22°56'30" N, 



64°56'10' 

 64°56'30' 



Eto 

 E 



Gulf of Oman 



18.11.1933 



1893 



AT 



106 



05°38'54" S, 

 05°40'18"S, 



39°15'42' 

 39°17'36' 



Eto 

 E 



Zanzibar 



12.01.1934 



183-194 



AT 



107 



05°15'30"S, 

 05°17'14"S, 



39°33'00' 

 39°32'48' 



Eto 

 E 



Zanzibar 



12.01.1934 



42 1-457 



AT 



118 



04°05'54" S, 

 04°17'00"S, 



41°10'12' 



41 11'48' 



Eto 

 E 



Zanzibar 



17.01.1934 



1789 



AT 



119 



06°29'24" S, 

 06°32'00" S, 



39049.54. 

 39°53'30' 



Eto 

 E 



Zanzibar 



19.01.1934 



1207-1463 



AT 



122 



05°21'24"S, 

 05°22'36" S, 



39°23'00' 

 39°22'18' 



Eto 

 E 



Zanzibar 



22.01.1934 



732 



OT 



143 



05°15'48"S, 

 05°13'42"S, 



73°22'48' 

 73°23'36' 



Eto 

 E 



Maldive Is. 



30.03.1934 



797 



AT 



145 



04°58'42" S, 



73°16'24' 



E 



Maldive Is. 



02.04.1932 



494 



AT 



158 



04°42'30" S, 

 04°36'48" S, 



72°42'30' 

 72°48'54' 



Eto 

 E 



Maldive Is. 



07.04.1934 



786-1170 



AT 



176 



12°04'06"N, 



50°38'36' 



E 



Gulf of Aden 



02.05.1934 



665-732 



AT 



180 



12°03'24"N, 



50°40'12' 



E 



Gulf of Aden 



02.05.1934 



397 



G 



184 



14°36'06"N, 

 14°38'42"N, 



51°00'18' 

 50°57'42' 



Eto 

 E 



Gulf of Aden 



04.05.1934 



1270 



AT 



185 



13°48'06"N, 



49°16'48' 



Eto 



Gulf of Aden 



05.05.1934 



2000 



AT 





13°48'36"N, 



49°16'24E 











188 



13°43'18"N, 



47°56'54' 



Eto 



Gulf of Aden 



06 05.1934 



528 



AT 





13°46'00"N, 



47°50'42 E 











193 



13°06'12"N, 



46°24'30' 



Eto 



Gulf of Aden 



07.05.1934 



1061-1080 



AT 





13°03'00"N, 



46°21'42"E 











AT - Agassiz trawl, OT - otter trawl, TD - triangular dredge, G - grab. 



The new species resembles Drillia tasconium Melvill & 

 Standen, 1901 from the Persian Gulf but differs in the high spire, 

 larger and more solid shell, and absence of spiral sulci which 

 deeply furrow the subsutural area in D. tasconium. 



Distribution. Gulf of Aden, 655-732 m. 



Genus HORAICLAVUS Oyama in Taki & Oyama, 1954 



Type species: Mangelia splendida A.Adams, 1867 (original 

 designation) 



Horaiclavus splendidus (A. Adams, 1867) 



Figs 20 & 21 



Mangelia splendida. A.Adams, 1867, p. 309, pi. 19, fig. 24. 

 Horaiclavus splendidus (A.Adams) -Shuto, 1965, p. 154-155, pi. 



29, figs 13-15, text-figs 3, 5; Powell, 1966, p. 142, pi. 23, fig. 13; 



Habe, 1970, p. 120, pi. 38, fig. 13; Kuroda et al, 1971, p. 



212-213, pi. 55, fig. 4; Shuto, 1975, p. 166, pi. 6, fig. 17. 



Type locality. Goto Islands, Japan. 



Material, stn 176, 3 shells; 188, 1 shell. 



All the JME shells, unlike the specimens illustrated elsewhere, 

 are uniformly coloured; the colour has probably faded since the 



time of collection. The protoconch consists of about 2.5 whorls, 

 with very small and adpressed initial volution. This is more than 

 in the holotype (Shuto, 1 975, pi. 6, fig. 1 7; though it is impossible 

 to evaluate the exact number of volutions from the lateral side of 

 the illustrated shell) and in Pleistocene shells (1 2/3 whorls, 

 Shuto, 1965). 



The JME shells are more similar to Japanese shells than to the 

 geographically closer H. madurensis (Schepman, 1913). The 

 latter species has somewhat broader and much smaller shell 

 (holotype is 14.8 mm in height at 8 teleoconch whorls, according 

 to Shuto, 1970, vs. 27.8-32.8 mm at 8-9 whorls in the JME 

 shells) with shorter canal and weaker ribs. However in fact these 

 species differ only slightly from each other, and H. madurensis 

 seems to have no more than subspecific status. 



The familial position of Horaiclavus is still uncertain. Its 

 radula was never figured, though Oyama (Taki & Oyama, 1954) 

 mentioned that it is similar to that of Comitas and Inquisitor. 

 Shuto (1983) described the radula of Horaiclavus as 'true 

 toxoglossate according to Kuroda, Habe and Oyama (1971, p. 

 327)'. However, the cited page contains no information about 

 this genus. Until the examination of the radula, I have to follov 

 Shuto (1975, 1983) in assigning Horaiclavus to Drilliidae. 



Distribution. Japan, 50-200 m, and Gulf of Aden, 528-732 

 m. The present record is a considerable geographic as well as 

 bathymetric range extension for the species. 



