PORIFERA. II. 



113 



length is generally 0-29 — 0-4""", but, as before mentioned, transitions to the skeletal spicules are found, 

 especially among the spicules that are placed immediately below the dermal bundles. The thickness 

 is 0-009 — 0'0i8 mm , but in some individuals it does not exceed o-oi4 m "\ Of the skeletal spicules devel- 

 opmental forms were seen, down to quite fine ones, but in very small numbers, b. Microsclera ; these 

 are of two forms, isochelse palmatce and toxa with spined ends. 1. The chela? are of the common 

 form; their shaft is about straight or quite slightly curved, the middle part between the two 

 terminal parts is straight or a. little curved inward; the length of this middle part is generally some- 

 what less than one third of the whole length. The tooth is about as long and broad as the alse. 

 The chelse vary somewhat as to size, and this may again to some degree influence the dimensions of 

 the different parts. The length is 0-007 — o-oi28 mm , most frequently near the latter size; the breadth 

 is ca. o-oo2 mm . Developmental forms were seen singly as quite thin, recurved staves. 2. Toxa. The 

 general form of these is one that has in the middle a strong curve while the ends are evenly curved 

 to the opposite side, and their outer part is most frequently straight. They are generally more or 

 less twisted in the middle, and most so, it would seem, in the smallest bows. From the mentioned 

 and by far most common form they ma)- vary in different ways, especially so, that the curve in the 

 middle becomes more open and the legs more straight, so that we may get a bow with a very great 

 angle and only one curve. The outer ends of the bow are spined for a quite short way; the spinosity 

 mav be a little varying, but generally there are comparatively few, rather coarse spines. These bows 

 are exceedinglv varying as to size; thus the length, which is somewhat dependent on the curve, 

 varies from o-07 mm quite up to o-32 ram ; the thickness, which is the same through almost the whole 

 length of the bow, varies in proportion to the size from about o-ooi — o-oo4 mm . All these sizes must be 

 regarded as fully developed bows; neither would the small ones by a continued apposition grow to 

 the form of the large ones, and they have likewise all, also the smallest ones, spined ends. On the 

 other hand small bows occur, thinner than the fully developed ones of the same size, and almost not 

 at all spined, or only with small spines; these, no doubt, are developmental forms. Thus the spines are 

 not found from the beginning, but only formed by and by. Of the microsclera the chelse are found 

 in exceedingly large numbers both in the dermal membrane and throughout the tissue, the bows are 

 found in the tissue in somewhat smaller numbers. 



As I have examined the type-specimen described by Schmidt I.e., I have been able with 

 certainty to establish the specific identity between Schmidt's Suberites arciger and Vosmaer's Arte- 

 iii is in a suberitoides. Already Fristedt 1. c. draws the attention to the probability of the identity. It 

 may easily be understood that Schmidt has overlooked the chelae, as they are exceedingly small, 

 their smallest size being perhaps the smallest chelae occurring at all. Schmidt further states that 

 besides the common needles a form occurs which variirt von der Kugelform bis zur Gestalt einer 

 kurzen, an beiden Enden stumpfen Nadeb, and he figures two such bodies; this fact, together with 

 the chelae, has for Vosmaer been the reason why he has not united the two species. The bodies 

 mentioned by Schmidt are, however, only monstrosities of the kind that is upon the whole not 

 rarely found in sponges. It seems especially to be the dermal spicules, which are sometimes trans- 

 formed in a monstrous manner. 



Locality: Station 28, 65 14' Lat. N., 55 42' Long. W., depth 420 fathoms; Station 127, 66° 33' 



The Ingolf-Expedition. VI. 2. 15 





