306 Dr. T. Wright on the Strorabidae of the Oolites, and 



it is contained in the following lines : — " Bei einigen See-krus- 

 tenthieren naraentlich bei der Gattung Lucifer (Thompson) babe 

 ich ganz neuerdings an der Wurzel der innern Fiihler einen klei- 

 nen runden glanzenden Korper entdeckt der mir dasselbe Organ 

 (auditory organ) zu seyn scheint." — Froriep's Notizen, 1843, 

 p. 83. 



EXPLANATION OF PLATE XIV. 



Fig. 1. The line indicates the natural size of the animal in this and the fol- 

 lowing figure : a, internal antennse ; 6, external antennae ; c, basal 

 lobe of external antennae ; d, eye ; e, otolithic sac. 



Fig. 2. Head of Palwmon. Letters as hi fig. 1. 



Fig. 3. Internal antennae of Palxmon enlarged : a, spine ; b, auditory sac ; 

 c, pigment-granules ; d, curved line to which the hairs are at- 

 tached ; e, otolithe ; /, antennal nerve. 



XXXI. — Contributions to the Paleontology of Gloucestershire : — 

 On the Strombidae of the Oolites. By Thomas Wright, M.D. 

 With the desmption of a new and remarkable Pteroceras. By 

 John Lycetf, Esq.* 



[With a Plate.] 



Among the remarkable new forms of extinct gasteropodous 

 mollusca which have from time to time been brought under the 

 notice of the Members of this Society, there are none more in- 

 teresting or more valuable as contributions to the oolitic fauna, 

 than the winged shells belonging to the genera Pteroceras and 

 Mostellaria. 



The Strombidce were first recognised as a distinct group of gas- 

 teropoda by Lamarck, in which this learned zoologist assembled 

 several forms having affinities with each other in the singular 

 development of the outer lip of the shell ; with these he formed 

 his family des Ailees, and which includes the genus Strombus of 

 Linnaeus, and corresponds with the Strombidce of modern natu- 

 ralists. 



This family is well characterized by the form of the shell and 

 that of the animal. The shell in the young state is conical or 

 spindle-shaped j after having grown in a regular manner for a 

 longer or shorter period of time, its farther development is ar- 

 rested, the outer lip becomes dilated, thickened and enlarged iu 

 a very remarkable manner, and sends out often long digitatious ; 

 the anterior part of the mouth terminates in a canal accompanied 

 with a more or less distinct siuus. The animal has the foot di- 

 vided into two parts, the one posterior cylindrical and obliquely 

 truncated and supporting a horny operculum. The other part is 

 flat, rounded before, and adapted for attaching the mollusk to 

 solid bodies. The bead is large and thick, and is prolonged into 



♦ Read before the Cotswold Naturalists' Club. 



