280 AGALMA OKENI. 



much in general appearance that they are easily recognizable. In the former 

 the gonophores are stalked and loosely clustered, and the gonophores them- 

 selves are comparatively large, with their cavities entirely' filled by the swollen 

 spadix. In the 9 , the individual gonophores are much smaller, each contain- 

 ing but a single large egg, and they are closely crowded on one main stalk (Plate 

 17, fig. 13). 



The palpons (Plate 17, fig. 14) are of the usual type, each bearing a contrac- 

 tile filament near its base. The siphons show no features of special interest. 



Tentilla. The tentilla deserve special mention, since it was a supposed 

 diversity in these organs which lead Lens and Van Riemsdijk to separate the 

 Agalmas ("Crystallomias") of the "Siboga" Expedition into two groups. These 

 authors describe four types of tentilla. Of these, types III and IV, as they them- 

 selves recognize, are merely successive stages of one type, which is the usual 

 condition in all but the youngest cormidia. The others, I and II, are small, 

 and occur only on a few of the oldest cormidia. It is according to the presence 

 either of I or of II, on the earliest formed tentacles, that they limit their two 

 groups of Agalmas. All these kinds of tentilla occur in the "Albatross" series, 

 and the better material allows me to state definitely that there is no essential 

 difference between types I and II of Lens and Van Riemsdijk. Indeed, accord- 

 ing to their own account both have a closed involucre and from one to two and 

 one half turns of the cnidoband, with the terminal filaments and ampulla typical 

 of the genus. The only difference between the two is that in II the lateral 

 filaments are coiled, in I they are not. This is an umimportant feature, so 

 much so that I have seen both types on one tentacle. In younger stages of 

 their tj^pe I + II the involucre only partially encloses the cnidoband and the 

 earliest stages are indistinguishable from those of the type described below. 

 This small form of tentilla, with but few coils, is characteristic of the oldest 

 siphons. I have never found an individual with moi-e than one tentacle of this 

 sort, and only two showing them at all. But Lens and Van Riemsdijk found 

 examples with as many as four such cormidia. In the later formed cormidia 

 the tentilla are much larger, as those authors observed and the cnidoband has 

 many more coils when matui'e. The involucre, at first only a basal swelling 

 (Plate 17, fig. 4j, encloses more and more of the coils with its progressive, 

 development (Plate 17, fig. 5, 6), and may finally enclose them all (Plate 17, 

 fig. 7). But there is evidence that it does not always do so, for I have found 

 old tentilla with up to as many as seventeen coils of which at least half pro- 

 truded, while others on the same tentacle had only fiom seven to nine, all 



