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184 



THE OPIIlURIDiE. 



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 ^ 



Side mouth shields very conspicuous; short and broad, meeting broadly 



within. 



First and second ventral plate not so large as those beyond; outer edge 

 curved, inner edge a little concave ; those beyond with outer and inner 

 edge straight; they all have laterals re-entcringly curved, and, except the 

 first, outer corners rounded. They are much broader than long. From about 

 the fifth joint the inner end of the ventral plates is deeply sunk^ so that they 

 appear separated, but are not so really ; they are all broadly in contact. 

 Side arm-plates short, but rather thick, the outer edge remarkably shiuous, 

 where the arm-spines are inserted ; they are separated above and below. 

 Dorsal plates with outer edge strongly curved, inner angle truncated, sides 

 straight; they are about equally broad and long, on the inner part of the 

 arm somewhat broader (a little too broad in Figure 6). The two-three 

 inner ones more or less rudimentary, separated from the radial shields by a 

 row of 2-3 thick plates to each side and one median. 



Disk very small. The radial shields separated by a single scale or some 

 few large ones ; in the interbrachial space there is only a single row of scales, 

 but at the margin there are more small ones. Usually a rather large central 

 plate and some smaller irregular ones around it. Primary plates sometimes 

 distinct, sometimes not. The radial shields are a little more than half as 

 long as the radius of the disk. All the plates of the dorsal side arc thick 

 and swollen, but perfectly smooth. The ventral side of the disk covered 

 with much smaller irregular scales ; genital scales small and inconspicuous. 

 The genital slits very short, but distinct. 



One large round tentacle scale. Three short, broad, flat arm-spines; 

 the upper one especially has become very broad and large, so that it appears 

 like a supplementary plate on each side arm-plate. Indeed, Lyman regards 

 it as such in S, nmrrhina. On paring it off, the side arm-plate of the next 

 joint is seen beneath it, so there cannot be any doubt that it is really an 

 unusually developed arm-spine. 



Color in alcohol: white, with light brown bands on the dorsal side. 

 Each arm has two longitudinal bands, one an each side of the dorsal plates. 

 Those of two opposite arms are continuous over the disk, those of the 

 other arms mostly united at the base of each arm. Finally, there is usually 

 a little band in each interbrachial space. 



Several specimens from Station 3405, 53 f 



This fine species is very nearly related to S. miirrhina Lym., from the 



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