ATLANT. DEEP-SEA EXPED. 1910. VOL. IV.] 



SPONGIA. 



21 



reticulated appearance owing to the close-set grooves 

 separated by narrow ridges — most like that of DendorLcella 

 rhopalum Lundb. (17, p. 127, pi. IV, fig. 4 & 5). 



Skeleton. The dermal membrane of the ridges 

 is supported by more or less erect or horizontal fan-like 

 brushes of tornota, with their free ends projecting beyond 

 the surface. The membrane of the grooves has only 

 iso chelae. The choanosome consists of dendritic and 

 anastomosing polyspicular strands of oxea. The outer- 

 most ramifications bend towards the surface at more or 

 less acute angles. 



Spiculation: The spicules of the ectosome are 

 tornota, often verging upon oxea, about 9.925 mm. long 

 and 0.018 mm. thick and usually straight. 



The spicules of the chanosome are straight or 

 usually slightly and evenly curved oxea, generally of equal 

 thickness through-out their length. They are usually 1.5mm. 

 in length and 0.037 mm. in thickness. The Microsclera, 

 exceedingly abundant in the dermal membrane, but also 

 usually present in the choanosome, are isochelce arcuatce 

 with a strongly curved shaft, somewhat laterally compressed 

 and with tooth-like alae, which are of about the same 

 length as the rather short tooth resting on an oblong 

 little tubercle. The length varies from 0.045 mm. to 0.063 

 mm. and the thickness of the shaft is about 0.0037 mm., 

 seen from the front. Several developmental forms were 

 observed. 



The specimen above described shows a striking resem- 

 blance to Desmacidon abyssi Topsent == Dendoricella 

 abyssi (Topsent) Lundbeck (41, p. .204) but in many 

 respects also to Dendoricella rhopalluin Lundbeck (17, p. 

 127)— both inter se closely allied deepsea-forms, but from 

 rather different localities, the one (D. abyssi) having been 

 recorded (5 specimens) from the Azores (4020 — 5005 m.) 

 and the other (D. rhopalluin) from Denmark-strait and 

 Davis-strait (20 specimens; depth 2076—2625 m.). The 

 "Michael Sars" specimen is from a locality intermediate 

 between those mentioned although belonging to the same 

 area as D. abyssi. I therefore think it must be referred 

 to Dendoricella abyssi (Tops.) Lundb. -if not to the typical 

 form, at least to a variety. 



Locality: The "Michael Sars" specimen was 

 obtained at the southern entrance of the Bay of Biscay 

 (45° 26' N, 9° 20' W), 4700 m. Globigerina ooze. 



Grayella fallax (Topsent). 



Syn: Yvesia fallax. Topsent 34, p. 106. 



(PI. II, fig. 3). 



St. 37. One specimen. 



In external appearance the specimen in hand does 

 not much resemble the type figured by Topsent (op cit. 



pi. VI, fig. 13), being 14 cm. long and about 7 cm. in 

 breadth with erect conical lobes diverging from a some- 

 what narrow base, while the type-specimen is a little 

 massive sponge, "sans papilles, ni pedicelle, 8 mm. cubes 

 de volume". The colour in spirit is yellowish. The 

 surface is minutely granular, and the dermal membrane 

 rather pellucid and easily detached (for large parts of it 

 have been rubbed off). 



The spiculation agrees better with that of Grayella 

 (Yvesia) fallax Topsent than with that of any other species 

 of the genus. 



Spiculation: The smooth, straight tornota for- 

 ming the main skeleton, are 0.266 mm. long with a 

 thickness of 0.006 mm. The spined, curved styli of the 

 dermal membrane varying from 0.111 — 0.185 mm. (thick- 

 ness 0.006) are somewhat longer than in the type. The 

 isochelae of the same shape as those figured by Topsent 

 op. cit. pi. X, fig. 14 c, are 0.016 mm. long. 



Geographical distribution. Grayella (Yvesia) 

 fallax Topsent has been recorded by the "Hirondelle" 

 from the Azores (st. 226— between Pico and Fayal), 

 depth 130 m. on a bottom of "gravier, sable et coquilles 

 brisees". 



The "Michael Sars" specimen was taken between 

 Gran Canaria and Cape Bojador (lat. 26° 6' N, long 14° 

 33' W); depth 39 m.; on a bottom with shingle, at a 

 temperature of 15.63° C. 



Echr'noc/athr/a Carter. 



Vide litter : 6, p. 204, 21, p. 159. 

 Echinoclathria hjorti sp. n. 



PI. II, fig. 5 & pi. V, fig. 3. 



St. 37. One specimen. 



A digitate sponge with flat branches anastomosing 

 in one plane, thus assuming the outline of a fan about 

 28 cm. high and 20 cm. in the broadest part. The 

 texture is rather tough and parchment'ike. The surface 

 forms a reticulation of very fine meshes, 0.5—1 mm. in 

 diameter. The trabeculae between the meshes have their 

 edges turned outward making the surface minutely uneven. 

 The dermal membrane (mostly rubbed off) is thin and 

 opalescent. The colour of the interior of the sponge is 

 pale dirty yellow. Oscula scattered. 



Skeleton consists of a rather close reticulation of 

 strongly developed horny fibres cored and echinated by 

 robust smooth styli. 



Spiculation. The megasclera are: 1) robust 

 smooth styli, straight or somewhat curved, sharply or 

 gradually pointed, often with a slight restriction above the 

 base, varying in length from 0.185 to 0.444 mm., with a 

 thickness of 0.030 mm. near the base. Generally the 



