56 THE DISCOBOLI. 



intra marginem scrie dentLculorura minimoruin, basi cylindraceorum, apice trilobo termina- 

 torura, quales ia nuUo pisci observavi. Oculoruin iiides angusto circulo pupillari fulvo. 

 A maxilla superiore utrinqiie processus sub cute tenuis osseus, quasi zygoma, per discum 

 operculorum. Opercula moUia rotundata, una cum membranis brancLiostegis sexradiatis 

 undique pelle adnata, relicto tantum spiraculo lunato utrinque ad dorsum. Corpus alepido- 

 tura, alvo teretiusculum indc compressum, cauda cathetoplatea. Cutis ubique fusco-puuctata, 

 mollis. Color in dorso lutescente fuscus, subtus fulvescens ; liturse rotundatae fuscae secun- 

 dum lineam lateralem. Striga argentea a maxilla superiore per oculum et opercula. Pinnse 

 pectorales fere ad jugulum positae, longiuseulae, radiis mollibus, tenuissimis. Cotula jugularis 

 inter membranas branchiostegas sita, parva, carnosa, ruga medii disci pinnata. Pinna dorsi 

 anique fere ad caudam continuatce, prior radiorum 33. paulo pone spiracula incipiens, altera 

 ab ano, circa medium longitudinis, radiorum 24. Caudae pinna fusco-nebulosa, longiuscula, 

 subiequalis, rad. 15. 



" Ad Camtschatcae pariter ct insularem littora frequenter a fluctibus ejicitur. 



'' Camtschadalis Cana'is. Aleutis Tomdogdak." 



Anatomy. 



In the solidity of its skeleton this species approaches closely to L. mii- 

 cosus ; its bones are nearly as firm as those of most ordinary bony fishes. 

 On the top of the skull the frontal ridges spread more rapidly, and make 

 a much more open curve, than those of the species mentioned. These 

 ridges, and those behind the turbinals, are moderately prominent. As 

 in L. mucosus, there is a strong ridge from the lower limb of the pre- 

 operculum to the articulation of the operculum with the hyomandibular. 

 The operculum has less of the boot-shape; it is nearly represented by 

 that of L. Agassizii in Plate III. Figure 2. In the suboperculura the an- 

 terior limb is the longer, stronger, and more curved. Half of the greatest 

 length of the suborbital chain is comprised in the spine-like extension. 

 The upper limb of the preoperculum is moderately broad. By the forms 

 of their teeth the larger specimens of L. mucosus and L. calliodon are 

 readily distinguished from the other species. The shape of the teeth of 

 L. calliodon is shown by Figure 5 of Plate VI. ; they are smaller and 

 more harsh than those of L. mucosus. In both of these species the 

 cusps are broadened, rounded, and compressed, instead of being conical 

 and pointed, as in most other cases. The plates on the hindmost ver- 

 tebra are of equal length; the lateral ridges on the upper are sufficiently 

 distinct. 



The brain is elongate ; the olfactory nerves are short ; the hemispheres 

 and optic lobes are about equal in size ; and the cerebellum is slightly 

 larger, extends back to the posterior lobes, and exposes a margin of con- 



