148 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Siphonoporella to us are only simplified Steganoporella. The genus 

 is usually equatorial although in the Southern Hemisphere it reaches 

 the fortieth parallel. 



LABIOPORELLA CRENULATA Levinsen, 1909 



Plate 16, figs. 2, 3 



1909. Labiopora crenulala Levinsen, Morphological studies on the Cheilo- 



stomatous Bryozoa, p. 174, pi. 6, fig. 4. 

 1926. Labioporella crenulala Harmer, Polyzoa "Siboga" Expedition, p. 282, 



pi. 21, figs. 1-3. 



Measurements. — 



Opesiumf *° - — — ' Zooecium f p = °^-° f mm ' 



v Uo = 0.15mm. \lz = 0.30-0.35 mm. 



^ v u • \Lon = 0.87 mm. 

 Onvchocellanum< 7 



Uon = 0.30 mm. 



An excellent specimen provided with its ectocyst shows that the 

 opercular valve is removed from the mural rim; it is semielliptical 

 elongated, bordered by a sclerite; its straight border for articulation is 

 placed at the middle of the height of the opesium which is quite 

 visible by transparency. This is indeed the structure in the opercular 

 valve of Onychocella and related genera and not the operculum 

 detachable from the ectocyst of the Aspidostomatidae. 



The polypidian lamella is an incomplete fragment of a kind of 

 polypide tube placed between two opesiules, but in this species the 

 tube is often complete. 



In spite of exterior appearances there is no true onychocellarium; 

 the mandible is not bimembranous but is a spatulate chitinous mem- 

 brane having the exact form of the cell in which it is inserted and 

 which resembles absolutely that of Siphonoporella. 



The presence of the polypidian lamella, the absence of ovicell and 

 the form of the avicularian mandible are characters of the Stegan- 

 oporellidae in which family it is necessary to classify this genus. 



Biology. — The avicularian mandible is fragile and the muscles are 

 feeble for they are detached easily when the specimen becomes dry. 

 Our living specimens had an ectocyst of a light color without any 

 trace of special pigmentation. They incrusted nullipores, bryozoa, 

 and dead shells. "The opercula are yellowish in color, the mandibles 

 are somewhat darker and the sclerites of both structures are brown" 

 (Harmer). 



Occurrence. — 



D. r,137. Jolo Light, Jolo; 6° 04' 25" N.; 120° 58' 30" E.; 20 



fathoms; S., Sh. 

 D. 5147. Sulade Island; 5° 41' 40" N.; 120° 47' 10" E.; 21 

 fathoms. 



