6 Prof. W. C. ]\l'Iiito.sli on certain 



Tlins in NorlJnn cnnnhijhfja tlic tube; proper i.s, in tlie 

 Zetlandic examples (fig. 1*), composed of the tougli and 

 glistening- secretion, strengthened externally by entire shell- 

 valves, large fragments of the latter, ])ieces of sea-urchins 

 and heart-urchitis, or, in those procured by the ' Knight 

 Errant' in 608 fathoms in the Atlanticf, of coarse gravel; 

 while occasionally the flattened tube is fixed to the valve of a 

 small scallop. ]t is usually straight, and the perfect valve of 

 the shell is terminal. The architecture is primitive, yet in 

 keeping with its surroundings. The tube, moreover, can be 

 carried about by its inhabitant, which has horny and calca- 

 reous jaws, so that it is in all probability sufficiently pro- 

 tected in the deep water where it is generally found. 



The tubes of the representatives of this genus procured by 

 the ' Challenger' exhibited some noteworthy features. Thus 

 in one {Nortliia somhreriana) the flaccid tube was supported 

 laterally by the long glassy spicules of a Hexactinellid sjionge, 

 which projected beyond each extremity. Another [Nortkia 

 ohrancliiata) had its flexible tube protected by long, monill- 

 form, brownish arenaceous Foraminifers, or by spines of 

 heart-urchins, shells and stones. Similar tubes characterize 

 Northia fycnobr and i lata. ^ but with the addition of a few 

 white tubes pertaining to the Serpulidre. A curious variation 

 was observed in a species {\or(/iia macrohrancJiiata) inhal)iting 

 the greenish mud at 350 fathoms off the coast of Japan 

 (Jedo), which utilized the long linear leaves of the pines 

 swept down by the rivers, besides leaf-stalks and leaves, 

 strawSj stones, and fragments of echinoderms, to strengthen 

 its tube of greyish mud. All the foregoing, however, though 

 considerable sl<ill is evinced in the manner in which the 

 foreign bodies are fixed to the tube, fall far short of the 

 wonderful ingenuity which characterizes a species [Korthia 

 WiUemoesli) dredged off Amboina. This annelid constructs 

 a firm rounded tube — curved in the form of a she|)herd's 

 crook — of greyish sandy mud, lined by a tough whitish 

 secretion. The ventral curve of the tube is comparatively 

 smooth externally, but the rest of the surface (and especially 

 the ])osterior curve) is furnished with a series of long, 

 slightly bent, sharp elastic spines, which are formed of layer 

 ujion layer of a hyaline secretion similar to that which lines 

 the tube, a well-formed central cavity giving the process, 

 moreover, a resemblance to a large sj)ongo-s])icule. 'J'he 

 distal region of the s])ine is veined like a finely marked pieee 

 of ])itch-pine, its central })ortion is ])laited or folded in some 



Tlu' fifrnro.*, ^villl (lie tvxi'Ojilioii of no. .'$, \v(>ro kiiuUy diawii iVom 

 imfiivt' l)v iiiy JVi/i'iiian, Mr. .1. M. Aiidrrson. -M.A. 

 i Kindlv .xciii hv i'r. .loliii Miirrav. 



