272 MR. P. H. GOSSE ON THE CLASPING- ORGANS 



ridges, where the substance deepens in hue, often to an intensity almost black (but still 

 like black glass), and where it manifestly acquires great density, elasticity, and hard- 

 ness, with a reflective power equal to that of polished glass. The gleam and glitter of 

 the surface imparts a wonderful attractiveness to these most diversified organs. The 

 parts thus thickened are also elevated, not merely in the bounding walls and ridges that 

 I have mentioned, but, in general, by the separating of a portion of the organ from the 

 cavity-floor ; so that this particular part shall be elevated, and projected freely into the 

 inclosed space between the valves. And these projected portions either take the forms 

 of curved acute spines, or, more frequently still, are notched into sharp teeth standing 

 in serried rows. 



To attempt to indicate the various forms which tbese curious weapons assume, would 

 be to anticipate the greater part of the descriptive pages which are to follow; for the 

 variety is about commensurate with the number of species examined. I propose pre- 

 sently to attempt a rough casting of them into groups ; but it will be little more than 

 an arbitrary classification, useful as an aid to memory, rather than any thing else. 

 Projecting claws, hooks, pikes, swords, knobs, and strange combinations of these, abound, 

 whose prominences are very commonly brought to a keen edge, and then cut into sharp 

 teeth. The species of one group, Agesllaiis, Parmatus, have harpes in which many 

 such projections arc strangely crowded. In others, Ulysses, Macedon, the formidable 

 teeth are themselves cut into many minuter toothlets of wonderful delicacy. 



Sometimes this polished weapon occupies almost the whole area of the valve-cavity, 

 Agesilaus, Podalirius, Erithonius ; sometimes it is a slender staff or rod, Memnon, 

 Erechtheus, Polymnestor, with the extremity expanded to form the weapon, whether 

 axe, or sword, or saw, or spear-point. Whatever the form, the base is always expanded, 

 often with ridges (like as where the trunk of a tree dilates into roots), spreading over the 

 basal edge of the valve, and manifestly stretching beyond its area, as is often very clearly 

 seen when the valve is forcibly detached. Examples of what I mean may be seen in 

 my figures of Papilio, Axion, Ascalaphus, Pammon, Ilacedon, Childrence, Verlumnus, 

 Zalmoxis, and several others. In all these a kind of disk is observed ; which more or less 

 clearly shows that there had been a dilated attachment of the harpe to a surface which 

 had lain in a plane quite different from that of the valve, face to face with it, indeed, 

 close to its hinge. (See, specially, Euryleon.) 



Hence I very confidently infer the function of two short thick eminences of hard 

 chitine, having convex surfaces, which are generally to be observed occupying the bottom 

 of the abdominal cavity, when the valves are removed ; e. g. 0. licmtts, P. Pammon, 

 Mlietenor, Mayo. They afford, doubtless, a broad and firm basis for the attachment of 

 muscles which move these important prehensores, so constantly exposed to shocks and 

 violent strains. And the fact of such an attachment explains an otherwise puzzling 

 phenomenon which not very infrequently occurs, — that, when the valve is detached by 

 force, it occasionally comes away empty, the chitinous armature being left behind. (See 

 infra, page 298.) 



If there existed any reasonable doubt of the work performed by this well-armed organ, 

 it would be removed by a due consideration of that curious accumulation of foreign 





