222 



anterior valve, except that in addition there are several well-defined growth sulci. 

 The posterior slope is slightly concave but steeper than in L. liratus. Commonly 

 in the latter species the mucro is more prominent, due to the posterior slope 

 immediately behind the mucro being almost vertical and then flattening out to 

 the girdle. 



Median valves. — The dorsal and pleural areas decorated with longitudinal 

 ribs composed of closely-packed, imbricating, flattened granules. In the dorsal 

 area, these pectinated ribs are very close together, but, in the pleural area, they 

 become further and further apart, until the interspaces are twice the width of 

 the ribs, these last becomng more raised, though still keeping the appearance of 

 closely-packed, semi-fused, polished, flattened granules ; some of the ribs only 

 traverse the area half-way, thereby leaving wider spaces between them, a feature 

 that is also characteristic of L. liratus. The lateral areas are narrow, raised, 

 decorated with radial ribs similar in character to those of the anterior valve, they 

 number 20 odd in type ; these radial ribs are crossed by concentric growth sulci 

 (9 in type). The type is not disarticulated, but a separated valve from Victoria 

 shows that there are no insertion plates ; sutural laminae small, far apart, inside 

 white. 



Girdle. — The underside is clothed with scales, which are imbricating, long, 

 flat, straight-sided, with rounded ends. The upperside is clothed with small, 

 irregular, arenaceous scales, which are almost hidden in perfect specimens by a 

 mass of short, slender, sharp-pointed, white spicules. 



Measurement. — The type, which is badly curled, measures about 20X65 mm. 

 The Port Arthur specimen, which is well preserved, measures 12X55 mm.; and 

 one of the specimens dredged by Mr. May off Schouten Island is 16X65 mm. 



Ha,bitat. — The type, which has been selected because in it the girdle spicules 

 have been well preserved, was dredged by Dr. Joseph Verco in St. Vincent Gulf, 

 and, passing through the hands of Dr. Torr, became the property of Mr. Tom 

 Iredale, to whom my thanks are due for presenting it to me for the purposes of 

 this paper. Dr. Torr has also several similar shells, also dredged by Dr. Joseph 

 Verco, but no data as to depth. Mr. W. L. May has dredged two in 15 fathoms 

 in Geographe Strait, Schouten Island ; six he dredged off the Pilot Station in 

 D'Entrecasteaux Channel, in 9 fathoms; and Mr. E. Mawle has dredged it off 

 Port Arthur at a similar depth ; also several specimens were dredged in Victoria 

 and are in the Bracebridge Wilson collection in the National Museum in Mel- 

 bourne. May and Torr (I.e.), referring to some of the specimens, say : "No 

 specimen, to our knowledge, has been taken near the shore." All the specimens 

 I have seen have been taken at depths varying from 54 feet to 135 feet, and 

 I have seen none but dredged specimens. 



In conclusion. — This species is easily distinguished from the New Zealand 

 L. inquinatus, Reeve, by its smaller scales . and very spiculose girdle ; from 

 L. liratus, Adams and Angas, by the sculpture in L. profundus, Ashby, being 

 less granulose, and more like polished, pectinated ribs ; the spicules in L. liratus 

 are much coarser, longer, and fewer in number, and the girdle scales of L. 

 liratus are larger and straight-sided, L. liratus also being consistently a littorine 

 shell. In both species there is incipient bridging between the ribs, but it is much 

 stronger in L. liratus than in L. profundus, although particularly regular in the 

 latter. In the centre of each flattened granule in the sculpture of L. profundus 

 occurs a black dot, which is the terminal of a sense organ which in more 

 specialized forms of chitons is developed into what are termed eyes. 



