123 



youth of the specimen. It has a group of six recurved spines just be- 

 hind the apex, and a series of small spines on the ridge which runs 

 on each side from the apex to the anterior angle of the eye. There 

 is also a small blunt spine on each side of the middle of the frontal 

 region ; and two others are placed on the bones over the hinder part 

 of the gill-flap. The latter form the commencement of a series of 

 carinated shields. The small scales are rough ; and the shields form- 

 ing the lateral lines are radiately grooved, and furnished with a sharp 

 continued keel, terminating posteriorly in a spine. The larger plates 

 on the hinder part of the body are smooth, with a few longitudinal 

 ridges, and emarginate at the apex. There are 1 7 plates on the dor- 

 sal ridge, of which the third is the smallest; 47 or 49 in the upper 

 lateral series, among which the anterior are much the smallest, their 

 length increasing gradually as they approach the tail, and this in- 

 crease being more marked after passing the ventral, and again after 

 passing the anal, fins; and 15 or 16 in the lower lateral series. 



The exhibition was resumed of the Shells collected by Mr. Cuming 

 on the Western Coast of South America, and among the Islands of 

 the South Pacific Ocean. Those exhibited at the Meeting were ac- 

 companied by characters bjj^ Mr. G. B. Sowerby, and comprehended 

 the following apparently undescribed species of the 



Genus Fissurella. 



FissuRELLA MAXIMA. Fiss. testd ovato-oMongd, depressiusculd, 

 crassd ; intiis albd, margine lato, imdiilato, pallescente fusco ar- 

 iiculato; extus radiatim sulcatd, rugosd, albido-cinerascente fusco 

 radiatd ; aperturd dorsali ovatd : long. 5, lat. Z A poll. 

 Hub. ad Valparaiso. 



In the young shells the internal margin is proportionally broader 

 than in those which are more fully grown : in some specimens this 

 margin shows a very great development of crystalline structure. 

 Found on exposed rocks and under stones at low water. — G.B. S. 



Fissurella grandis. Fiss. testd ovato-oblongd, elev alius culd, pos- 

 tice latiore, crassd ; intiis albd, margine lafiusculo, subundulato, 

 cinerascente ; extHs Icevigatd, piirpureo-nigrd, radiis numerosissi- 

 mis saturatioribns ; aperturd dorsali majusculd, oblongd, extHs la- 

 tiore, antice subdeclivi: long. 4, lat. 26 poll. 



Hab. ad Valparaiso et ad Insulam Chiloe sub lapidibus littorali- 

 bus. — G. B. S. 



Fissurella limbata. Fiss. testd ovato-oblongd, depressiusculd, 

 postice latiore, crassiusculd ; intiis albd, margine latiusculo, subun- 

 dato, pallescente, lined internd purpureo-nigrd ; extixs Icevigatd, 

 rosaceo-fuscescente, radiis rufescentibus ; aperturd dorsali elon- 

 gatd, mediuni subcoarctatd : long. 3, lat. 1-9 poll. 

 Hab. ad Valparaiso. 



In young shells the internal line of the margin is broader and more 

 deeply coloured than in the more fully developed specimens. Nearly 

 all the fully grown shells are so deeply eroded as to have lost almost 



