中文摘要：

实验室内对平疣桑椹石磺（Platevindex mortoni）和里氏拟石磺（Paraoncidium reevesii）的胚胎发育过程进行了详细观察,比较了两种石磺受精卵生物学数据之间的差异。结果表明,平疣桑椹石磺和里氏拟石磺的受精卵生物学数据存在显著性差异（P〈0.05）。分别记录两种石磺受精卵、分裂期、囊胚期、原肠期、膜内担轮幼虫期、膜内面盘幼虫期、孵化期7个发育阶段的胚胎大小和孵化所需时间,观察各期胚胎发育特征,并与瘤背石磺胚胎发育做比较。发现不同种石磺胚胎发育各期的主要形态结构并无明显区别,但是发育各期胚胎大小及孵化所需时间均有较大差异。在平均水温28℃,静水微充气,平均盐度15的条件下,平疣桑椹石磺、里氏拟石磺和瘤背石磺从受精卵到膜内面盘幼虫孵化分别需要210 h、253 h和270 h;死亡时间分别为产卵后的第25天、22天和24天。孵化后的自由面盘幼虫发育至匍匐幼虫期开始死亡,未完成幼虫培育过程,面盘幼虫的变态过程和变态条件仍有待研究。

英文摘要：

Onchidiidae is one of the higher clades of pulmonates. Most of them are marine organism and live in the intertidal zone, in rocky, sandy, or muddy habitats, including mangroves. In China, previous studies on Onchidiidae mainly focused on Onchidium struma. Platevindex mortoni and Paraoncidium reevesii are new record ones in mainland China. Their embryonic development process can be divided into seven stages： cleavage, blastula, gastrula, intracapsular trochophore, veliger in capsule and free-swimming veliger stage. The embryonic development of Platevindex mortoni and Paraoncidium reevesii were observed and described. The morphological characteristics of every period of larvae were recorded under microscopic observation, anti the time series table of embryonic and larval development was confirmed and compared with Onchidium struma. Results showed： different Onchidiid species have significant differences in zygote biological parameters and the time required for fertilized eggs to hatch. At the average water temperature of 28 ℃ and salinity of 15, the time period from the fertilized eggs hatching to the free-swimming veliger stage required for three Onchidiid species was 210 h, 253 h and 270 h respectively. We did not observe the development of larvae for they all died in creeping larva stage. More work still needs to be done to ascertain the condition and process of metamorphosis for pelagic veliger.