44 NATURAL HISTORY OF KERGUELEN ISLAND. 



Patella? delessertii, PhiMppi. 

 Mus. No. 11902. 



Straits of Magellan, authors ; Kergueleu, one dead specimen 

 probably of this species, Dr. Kidder. 



CHITONID^. 



Genus HEMIARTHRUM, Cpr., MS. 



Yalvse terminales laminatse, hand articulatae, laminse laterales obso- 

 letse; zona lanuginosa, porifera ; branchiae posticse. 



HEMIARTHRUM SETULOSUM, Cpr., n. S. 



Mus. No. 11903. 



H. t. latiore, curvata, olivaceo-fusca ; jugo plauato; mucrone sub- 

 centrali ? areis baud definitis ; tota superficie sensina quincunxiter 

 granulosa, granis satis^ extantibus. 



Intus ; valva antica et postica conspicue laminata; laminis acutis, 

 baud incisis, baud regularibus, valde extantibus ; subgrundis spongi- 

 osis, minimis; valvis centralibus et postica laminis suturalibus, tri- 

 angularibus, maxime distantibus, extantibus, decliviterlateraliter, conti- 

 nuis; sinu maximo, valde spongioso. 



. Zowa modica, baud expansa, solida, leve; sparsim minutissime lanu- 

 ginata; poris minutissimis, setuliferis ad. suturas, et circ. iv, circum 

 valvas terminales sitis, instructa, setulis minimis, curtissimiSc 



Animal, pede capiteque normalibus; branchiis majoribus posticis, 

 utroque latere circiter vi, medio pede tenus. Lon. 13"™. Lat. 7""™. 

 Div. variante ad 130°. 



Kerguelen Island, on stones at low water. Dr. Kidder, two specimens. 



This shell, externally, resembles some of the coarse, ill-defined acan- 

 thochitons. The girdle, however, is narrower and smoother than in 

 that genus, and the pores so extremely minute that in a dry specimen 

 they would escape attention. Within, however, the features are entirely 

 new, though not unexpected. It forms a transition between Hanleia 

 {mendicaria) and the articulate chitons. A single unslit lamina sur- 

 rounds both the terminal valves, projecting far beyond the external 

 layer. In the posterior plate this is continued forward to form part of 

 the sutural laminae. These, in all the valves, slope off, both toward the 

 middle and toward the sides, so as to take the place of the ordinary 

 side-laminae, which here do not exist. 



The specimen examined — hardened by preservation in alcohol and 



